More than 10,000 jobs at Royal Dutch Shell are under threat as Peter Voser, the oil giant’s new chief executive, announced a radical shake-up of the company.

In a series of moves designed to slash billions of dollars from Shell’s cost base and sharpen its focus in an era of low oil prices, the company said it was merging three divisions into two, creating a new one charged with project management and trimming the number of executive directors on its board from five to three.

“Organisationally, we are too complex, and our culture is still too consensus-oriented. Our costs are simply too high,” Mr Voser told staff in an e-mail before briefing 200 senior executives on the plans at a special meeting in Berlin.

While Shell refused to specify how many jobs would be lost in the reshuffle, analysts estimate it will be between 5 per cent and 10 per cent of the company’s 102,000 staff. Most of the cuts are expected in middle and senior management roles. About 24,000 Shell staff who work across the divisions that are due to be merged will be directly affected, although only some of these positions will be eliminated, a spokesman said.

The changes will initially affect Shell’s 200 most senior executives with some reports yesterday suggesting that more than 30 per cent of them would be dismissed. Hundreds of jobs in the UK, where Shell employs 9,000 staff, are also thought to be under threat.

The first casualty of the reorganisation came on Monday with the abrupt resignation of Linda Cook, Shell’s former head of gas and power and a 29-year veteran of the company.

Her division will be folded in with two other businesses that had previously been run as separate units: exploration and production – Shell’s core oil production business and the engine of its profits – and oil sands. Under the new structure, which places natural gas at the centre of Shell’s business alongside crude oil, these will be run together along regional lines: “Upstream Americas” and “Upstream International”.

In a drive to improve Shell’s patchy record delivering important projects on time and to budget, a new business – “Projects & Technology” – will combine all of Shell’s activities in these areas.

Shell is also reducing the size of its corporate affairs division, which is headquartered in The Hague, where it employs 2,000 people.

Mr Voser takes over from Jeroen van der Veer on July 1, when the changes will also be implemented, although the bulk of job cuts are not expected before autumn.

“These changes will increase our focus, accelerate our plans to reduce complexity, corporate overheads and costs, and result in faster decision-making and delivery,” Mr Voser said.

Up to 200 Shell executives from around the world flew to Berlin this week for an unusual two-day meeting.

The gathering, which began on Tuesday, offered a final chance to bid farewell to Jeroen van der Veer, the mild-mannered Dutchman who has steered Shell through some rocky times over the years. The chief executive is due to retire next month but the mood was hardly celebratory, for his replacement, Peter Voser, has wasted no time in making his mark.

The executives were also in Berlin to hear Mr Voser outline his plans yesterday for a radical overhaul at the world’s second-largest listed oil company. This will involve thousands of job losses, including many of their own.

Mr Voser, Shell’s chief financial officer for the past five years, has had plenty of time to prepare for this day. A drive to slash costs and boost efficiency by streamlining and simplifying the organisation formed a key part of his pitch for Mr van der Veer’s job.

In the past few years, Shell’s reputation – along with its share price – has suffered from a series of lengthy delays and budget overruns on huge deals such as the $22 billion (£13.7 billion) Sakhalin-2 project in Russia and the Pearl gas-to-liquids plant in Qatar.

In response, Mr Voser yesterday laid out a detailed plan to tackle these problems. “The industry, and Shell, faces considerable challenges, from high costs, volatile energy prices, and competition for new projects,” he said.

His solution is to follow in the footsteps of ExxonMobil, the industry leader, by creating a separate unit, Projects and Technology, responsible for masterminding large-scale projects with the aim of cutting costs. Matthias Bichsel, who like Mr Voser is a Swiss national, has been appointed to lead this division.

Mr Voser has taken the knife to thousands of jobs across Shell’s middle and senior management in a dramatic drive to slash costs and boost efficiency by merging three core divisions and cutting other regional businesses.

In many ways, the shake-up completes a transition that began in 2004 after a scandal surrounding the misreporting of Shell’s reserves of oil and gas, which highlighted concerns about the Anglo-Dutch oil group’s opaque decision-making structure.

It has also thrown up some telling power shifts within the organisation. Malcolm Brinded, Shell’s British head of exploration and production, who was once tipped as a rival to Mr Voser for the top job, will now lead Upstream International. This is one of two new businesses that Mr Voser has spun out of Shell’s Gas and Power, Exploration and Production, and Oil Sands businesses.

To ease decision-making at Shell – which has always been known for its “collegiate” approach – Mr Voser has decided to slash the number of executives who serve on the group’s board of directors from five to three.

One space opened up this week with the abrupt departure of Linda Cook, the American Gas and Power chief, who is the most high-profile victim of the reshuffle. The retirement this year of Rob Routs, Shell’s downstream boss, opened up another seat.

Under the new structure, Mr Brinded will continue to sit on a trimmed-down board along with Mr Voser and Simon Henry, Mr Voser’s replacement as chief financial officer.

Mr Voser claims the restructuring “will increase accountability in the company and improve Shell’s performance on delivering new projects and developing new technologies”.

In another move that reflects the growing importance oil companies attach to building relations with the US Administration of President Obama, a small, dedicated unit based in Washington has been created to oversee relations with the Government. This unit will be headed by Roxanne Decyk, Shell’s director of corporate affairs and sustainable development.

While the restructuring is likely to affect almost every one of the 110 countries in which Shell operates, the group’s headquarters in The Hague is expected to be worst hit.

Linda Cook, the head of Shell’s gas business, resigned abruptly yesterday, the first boardroom casualty at the hands of Peter Voser, the new chief executive of the oil company.

Mrs Cook, who fought Mr Voser for the top job, is leaving after a “mutual decision” with the new boss and is forgoing an £800,000 loyalty bonus because she is quitting before 2011. It is believed that Mr Voser, who is stepping up from chief financial officer, is in the process of choosing his new leadership team.

Mrs Cook’s departure comes as four large institutional investors were understood to have grown frustrated with her. They are thought to have found her grasp of the business outside her immediate gas operations to be “underwhelming”.

Big investors are known to have changed the dates and times of meetings with the company when it was clear that Mrs Cook was to have led the discussion. They then demanded to speak to other executives to discuss the group’s performance.

Mrs Cook, 50, is expected to receive a payoff worth at least £4.2 million, which represents the sum of last year’s total pay, excluding her pension. At the end of December her retirement pot — into which she has paid during her 29 years of service — was valued at $11.499 million (£7.22 million). It is not known whether Shell will enhance her pension arrangements as part of her departure package. The company declined to comment.

Mrs Cook’s replacement, as yet unnamed, has been earmarked and is said to be an internal candidate.

The £800,000 loyalty bonus that Mrs Cook will not receive was devised by Shell last year to try to retain key executives. It was calculated as equivalent to the executive’s annual basic salary in 2008. As such, Malcolm Brinded, the head of Shell’s exploration and production operations, will get £937,000 if he stays with the oil company for the next two years.

The retention bonuses were hotly debated by institutional shareholders and voted through with a reduced majority. Last week big investors rejected Shell’s pay report with 59 per cent voting against it, and several City shareholders lambasted the board over executive share awards.

The vote was an embarrassing blow to Sir Peter Job, who chairs the remuneration committee and rubber-stamped the loyalty bonuses. Sir Peter is no stranger to controversy over executive pay packages. The former head of Reuters, the financial news provider, also served on the remuneration committee of GlaxoSmithKline. In 2003 the drugs company awarded Jean-Pierre Garnier, its chief executive at the time, a £22 million golden goodbye.

At the Shell annual meeting last week Franklin Mutual, part of the giant Templeton group of funds in the United States, described as “pathetic” the defence offered by Sir Peter of the pay report and called for the resignation of the committee.

Its members include Josef Ackermann, the Deutsche Bank chairman and chief executive, and Lord Kerr of Kinlochard, the Shell deputy chairman and a former Ambassador to the United States.

Mrs Cook, who is Shell’s highest-ranking woman, will leave her post at the end of this week. Mr Voser will take the top job on July 1.

A Shell spokesman said: “She will continue to be available to advise the company on strategic and management developments in the near term and to ensure an orderly succession in Gas and Power. Linda’s replacement is the subject of a future decision, and there is no update on this today.”