The defence secretary has denied that Britain and American planes enforcing the no-fly zone in Iraq have begun launching attacks in preparation for war.

Attacks have been stepped up, however, with reports suggesting that surface-to-surface missile batteries that could target Western troops in Kuwait are now being attacked.

Geoff Hoon told the Commons yesterday that there had been no change in policy but there had been "more frequent patrols involving a broader range of aircraft".

The shadow defence secretary, Bernard Jenkin, said that "the opening shots of the second Gulf war" had already been fired.

Former Europe minister Doug Henderson said that the increased activity marked a "slide into war" while fellow Labour backbencher Alice Mahon said military action had begun through the "back door".

The Iraqi government said an attack at the weekend killed six civilians and wounded 15.

As the air campaign continues, the Telegraph reports that 300 SAS soldiers and thousands of American and Australian special forces are already conducting operations in Iraq.

Other military preparations for war continued yesterday, with giant American B-52 bombers arriving at RAF Fairford in Gloucestershire.