Hollow Shell

Royal Dutch Shell is to delay publication of key data about its oil reserves that it would normally have released alongside profits figures being published on Thursday.

The decision has disappointed some analysts, who have been told that the subject will not even be "up for discussion" and which has sparked concern the reserves numbers could be poor.

The amount of reserves booked by Shell is always a sensitive issue for the company as it was the revelation in 2004 that Europe's largest oil firm had overstated the amount of oil in its wells that led to the resignation of chairman Sir Philip Watts and investigations by regulators in London and New York.

Analysts at Kleinwort Benson said the decision to now publish the data in May was "regrettable". Another analyst said: "Since [the reserves scandal] Shell has been hot on releasing information to the market at its annual results. Putting it back doesn't mean there's a problem. But it doesn't inspire confidence."

Reserve replacement ratios are a measure of an oil company's health, as they compare the amount of new oil booked as recoverable with the amount of crude being pumped from wells. The lower the ratio, the lower the future returns. Shell's ratio in 2006 was 150pc, up from 78pc in 2005. Although oil firms are not required to publish data with profits figures, many do, or at least give the market a steer on the numbers.

"Our problem with this is not the delay per se, but the fact that we will not even get an indication," said an oil analyst. "It seems unnecessarily coy." Kleinwort analyst Colin Smith said: "We understand Shell will not comment on reserves and will not provide any details until publication of the 20F [an SEC filing in May] essentially because the reserve replacement has been weak and made more complex by the impact of the Sakhalin II transaction." It is thought that problems in Nigeria are another reason why the reserve replacement could be disappointing.

Shell said: "We think the right place to update on reserves is in the 20F." The firm did not expand on why.