Shell, which has angered investors by four times lowering its oil reserves estimate this year, has avoided a further stand-off with shareholders by releasing details of a corporate governance review.

The oil giant has named the executives overseeing the appraisal, and confirmed that it will consider simplifying its corporate governance structure, based around UK and Dutch boards.

Shell said: "Nothing is being ruled out at this stage."

The announcement follows criticism from major shareholders of the secrecy surrounding the review, which was launched in March, two days after the reserves crisis prompted the company to oust its chairman, Sir Philip Watts, and head of exploration and production, Walter van de Vijver.

Fears have grown that Shell would shy away from reviewing its twin-board structure, which many observers have criticised for creating confusion and allowing some executives, for months, to withhold knowledge of wrongly classified reserves.

Ted White, the director of Calpers, the California pension fund, and Eric Knight, the managing director of Knight Vinke Asset Management, said in a joint statement yesterday: "It remains our review that a portion for the blame for the reserves debacle is to be attributed to the prevailing corporate governance culture of the group and the absence of orthodox board structures."

The fund managers "explicitly" requested the publication of review details to allow shareholders to consider its terms ahead of the Shell annual meeting on June 28.

"There is a significant opportunity for the group to repair some of the confidence that has been lost by conducting this process in a manner that embraces openness and candour," the duo added.

Shell's statement this morning added that results of the review would be published in November allowing time for consultation ahead of a recommendation to be put before next year's annual meeting.

Shell shares stood 4p higher at 410.25p in afternoon trade.

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