The complaint was filed in Berlin November 30 by the New York-based Center for Constitutional Rights (CCR) and Berlin's Republican Lawyers' Association on behalf of four Iraqis who were alleged to have been mistreated by US soldiers.

Besides Rumsfeld, former CIA director George Tenet, Undersecretary of Defense for intelligence Steven Cambone, Lieutenant General Ricardo Sanchez, Brigadier General Janis Karpinski and five other military officers who served in Iraq were named in the complaint, which seeks an investigation into their role in the prisoner abuses at Abu Ghraib.

"Generally speaking, as is true anywhere, if these kinds of lawsuits take place with American servicemen in the cross-hairs, you bet it's something we take seriously," said Lawrence DiRita, the Pentagon's spokesman.

"If you get an adventurous prosecutor who might want to seize onto one of these frivolous lawsuits, it could affect the broader relationship. I think that's probably safe to say," he told AFP.

Germany is home to some 70,000 US troops, many of whom have rotated into and out of Iraq from German bases. Sanchez, the former US commander in Iraq, is stationed in Germany as commander of the army's 5th Corps.

The groups that filed the complaint said they had chosen Germany because of its Code of Crimes Against International Law, introduced in 2002, which grants German courts universal jurisdiction in cases involving war crimes or crimes against humanity.

It also makes military or civilian commanders who fail to prevent their subordinates from committing such acts liable.

DiRita said he did not know whether the United States has raised specific concerns directly with the German government.

But he said, "I think every government in the world, particularly a NATO ally, understands the potential effect on relations with the United States if these kinds of frivolous lawsuits were ever to see the light of day."