Opposition MPs have raised concerns after it was revealed the man in charge of MI6 will quit next year.

Sir Richard Dearlove will stand down in August 2004, the Foreign Office confirmed at the weekend.

Officials denied the decision was linked to the row over the war in Iraq.

The Conservatives called for reassurances that his replacement would not be closely linked to the prime minister after one newspaper claimed his successor is likely to be the head of the Joint Intelligence Committee, John Scarlett.