Van der Veer told reporters on a conference call that Shell made 11 material discoveries in 2007 and had an exploration success rate of 40 percent, yielding an extra 1 billion barrels of oil equivalent of resources.

A year ago Shell said it added "over 2 billion barrels oil equivalent of new conventional resources" in 2006.

Chief Financial Officer Peter Voser said both figures largely related to oil and gas added through exploration.

Voser noted that the latest figure excluded "business development" activities, which were included in the 2006 figure, so the actual performance in 2007 may not fall so short of the 2006 result.

"We are very satisfied," he told reporters on the call.