Donald Rumsfeld was under mounting pressure to resign today as he faced a sustained and growing chorus of criticism from America's military establishment over the Iraq war.

Two more retired generals, including Major General Charles Swannack who led the US Army’s 82nd Airborne Division in Iraq in 2004, accused the Defence Secretary of "absolute failures".

"We need to continue to fight the global war on terror and keep it off our shores," General Swannack told The New York Times. "But I do not believe Secretary Rumsfeld is the right person to fight that war based on his absolute failures in managing the war against Saddam in Iraq."

General Swannack's complaints were echoed by Major General John Riggs, a three-star general who left the Pentagon in 2004. General Riggs told National Public Radio that Mr Rumsfeld had instilled a culture of arrogance among the civilian administrators of the war.

"They only need the military advice when it satisfies their agenda. I think that’s a mistake, and that’s why I think he should resign," said General Riggs, who served in the army for 39 years.

The fresh resignation calls add to those already made by four other retired generals directly involved in the Iraq war and its planning.

Retired Marine Gen Anthony Zinni told CNN that Mr Rumsfeld should be held responsible for a series of mistakes, beginning with "throwing away ten years worth of planning, plans that had taken into account what we would face in an occupation of Iraq".

The swell of criticism against Mr Rumsfeld is apparently as un-coordinated as it is unusual. According to American press reports, senior generals are speaking out spontaneously, in defiance of a long-held military culture of maintaining strict official support for the civilian leaders of the Pentagon.

On Wednesday, Major General John Batiste, who commanded the 1st Infantry Division in Iraq in 2004-05, said: "I believe we need a fresh start at the Pentagon... We need leadership up there that respects the military as they expect the military to respect them."

Last weekend Lieutenant-General Greg Newbold, the former director of operations for the Joint Chiefs of Staff, wrote in Time magazine that the invasion of Iraq "was done with a casualness and swagger that are the special province of those who have never had to execute these missions — or bury the results". He added: "The cost of flawed leadership continues to be paid in blood".

Major-General Paul Eaton, who oversaw the training of Iraqi troops in 2003-04, wrote an opinion piece for The New York Times calling for Mr Rumsfeld to go because he was "incompetent strategically, operationally and tactically".

The charge against Mr Rumsfeld is that he dismissed his senior officers’ reservations about the Iraq battle plan. His critics cite the treatment of General Eric Shinseki, former Army Chief of Staff, who was sidelined after telling Congress before the war that he believed that several hundred thousand troops — many more than were used — would be required for a successful operation.

General Batiste’s comments have particular resonance within the Army because he was offered a promotion if he returned to Iraq as second-in-command. He declined and quit the military in November, reportedly because he no longer wished to serve under Mr Rumsfeld.

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