The crisis over the reserves of oil giant Shell claimed its third scalp today with the departure of finance chief Judy Boynton.

News that Ms Boynton had stepped aside emerged in a report into the circumstances around Shell's shock downgrade of its oil and gas stocks in January.

Shell lowered estimates of its proved reserves for the third time in as many months today, but said 90% of its global energy fields had now been reassessed.

The oil giant, which has already announced the departures of chairman Sir Philip Watts and head of exploration and production Walter van de Vijver, added that it was speeding up a review of its corporate structure.

Shell chairman Jeroen van der Veer said the report "draws a line" under the uncertainties over the group's reserves.

Shell announced today that reserves at more than one-third of its 300 oil and gas fields around the world had been adjusted since the crisis began in January.

A third marginal downgrade means its reserves at the end of 2002 will now be a combined 4.35 billion barrels lower than previously thought. There is also a further reduction of 500 million barrels for last year.

The impact on earnings from these changes averages over £55m for each year since 2000, Shell said.

The company is being investigated by the US Securities and Exchange Commission (SEC), while the Financial Services Authority in the UK has requested information regarding the circumstances around the reserves downgrade.

Shell is also facing a number of class action lawsuits in the US over the reserves downgrade and is being investigated by Dutch regulators over potential "insider trading".

Monday April 19, 2004