Mr Rumsfeld has become a prime target for international human rights activists since resigning last week from his post as defence secretary - his immunity from prosecution will soon lapse and, under German law, a non-German can be prosecuted for war crimes committed outside Germany.

The 300-page case for a criminal prosecution of the controversial US politician was presented today to the German federal prosecutor, Monika Harms, by the American and German lawyers representing 11 former Iraqi detainees of the Abu Ghraib prison in Baghdad and one former inmate of the US detention centre in Guantanamo Bay. As a result, Germany is preparing for a major new broadside against US policy in Iraq.

“These crimes were planned and executed at the highest levels of the US government,” said Michael Ratner, president of the Centre for Constitutional Rights, which is leading the campaign for a Rumsfeld prosecution.

The star witness against Mr Rumsfeld is the former governor of Abu Ghraib prison, Janis Karpinski. “When I arrived in 2003, the prison held under 500 Iraqis, but, within a month, after a visit by military intelligence, that number had jumped to 3,000,” said Mrs Karpinski.

“Within a further month, the prison was holding 7,800. There was no release procedure in place and most did not know why they were being held.”

She accused Mr Rumsfeld today of authorising the use of torture at the prison and effectively wresting the jail out of her control.

At a public hearing in Berlin today - to press home the prosecution case against Mr Rumsfeld - the former governor described how a senior military intelligence officer, Major General Geoffrey Miller, took command over the prison. He was, according to the case presented to a public hearing today, acting on the orders of Mr Rumsfeld to secure better and quicker intelligence from captured Iraqis.

“He simply said: ’I order you to hand over Abu Ghraib to me’,” recalled the former governor, who was disciplined and demoted after photographs of prisoner abuse were made public.

“Our testimony gathered from ex-prisoners and ex-military personnel shows that prisoners were beaten senseless during questioning,” said Wolfgang Kaleck, a leading German human rights lawyer who has helped formulate the legal case against Mr Rumsfeld.

“They were subjected to shocks with electric instruments, locked in boxes, hot substances were stuffed in their noses, chairs broken over their backs. They were screamed at, urinated upon and sexually abused.”

The accusations are familiar from the various reports that followed the first exposure of the Abu Ghraib abuse, but the lawyers - aided by Mrs Karpinski - want to convince the German prosecutor that they have established a chain of command leading back to Mr Rumsfeld and which takes in other senior administration officials. Since Mr Rumsfeld can no longer be legally shielded by his office, he has become vulnerable.

The former German prosecutor threw out an earlier attempt at a private criminal prosecution against Mr Rumsfeld in Germany. Human rights lawyers in Germany say this was the result of pressure by the US administration on Berlin.

Certainly, the timing was significant - the case was rejected on the eve of a planned visit to Munich by Mr Rumsfeld. Then, the prosecutor claimed that the United States was primarily responsible for prosecuting any alleged offences.

Now, however, the civil rights lawyers are arguing that there is strong new evidence against the former defence secretary.

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