Defense attorney Ladislav Anisic, who is representing Moroccan national Mounir El Motassadeq, on Wednesday filed a request with the court in the northern city of Hamburg to subpoena Zacarias Moussaoui, arguing that he could shed light on his client's role in the plot.

Presiding judge Ernst-Rainer Schudt said that the court would forward the petition to US authorities.

Washington, however, has repeatedly refused requests to allow terror suspects in its custody to appear at German trials related to the 2001 attacks in New York and Washington, citing security concerns and the need to protect secret information.

Setting a deadline

Ernst-Rainer Schudt said his court was still waiting for new files on the September 11 attacks that the US Justice Department had promised to provide.

"We may have to think about setting a deadline so we can get some movement on this," he said.

Motassadeq is being retried on charges of membership in a terrorist organization and accessory to the murder of some 3000 people for his alleged involvement in the so-called Hamburg cell that produced three of the September 11 hijackers. He was sentenced in February 2003 to 15 years in prison on the same charges.

At the time of his conviction, he was the only person to have been found guilty in connection with the attacks on the US. But a federal tribunal overturned the conviction in March 2004 on the grounds that his trial had not been a fair one because US authorities had failed to provide potentially exculpatory intelligence from alleged members of the Al-Qaeda extremist network in their custody.

One of them was Ramzi Binalshibh, a key suspect who said that the activities of the Hamburg group were not known to Motassadeq and that the cell consisted only of himself and three suicide hijackers. Defense lawyers argued that Motassadeq could not therefore be guilty.

Moussaoui pleads guilty

In a Virginia court on Friday, Moussaoui, a 36-year-old French national of Moroccan descent, pleaded guilty to six conspiracy charges linked to the September 11 attacks, including to carry out acts of terrorism, to commit aircraft piracy and to use weapons of mass destruction -- all of which are capital offenses.

Moussaoui is the only person in the US so far charged over September 11, and the US government has said it will seek the death penalty for him.

But he has insisted that he was not to be one of the September 11 hijackers and that he was to take part in a later attack on the White House.

In 2001, he was arrested one month before the attacks in immigration charges.