Key US hearing for 9/11 suspect

Mr Moussaoui denies involvement in the 9/11 plot

A US appeals court is examining the case of Zacarias Moussaoui - the only person charged in the US in connection with the attacks of 11 September 2001.

Defence lawyers argue that Mr Moussaoui, who could face execution if convicted, should be allowed to call detained terror suspects as witnesses.

The government says that calling such witnesses - including two top al-Qaeda operatives - would be a security risk.

Mr Moussaoui admits al-Qaeda links but denies involvement in the 2001 attacks.

During pre-trial hearings a US district judge ruled that Mr Moussaoui, a French national, could not be put to death as he had been prevented from questioning other terror suspects for his defence.

I think there's no way that he can defend himself without being able to obtain the evidence from these witnesses Frank Dunham Defence lawyer

And defence lawyers argue that under the US constitution anyone facing the death penalty has the right to choose witnesses.

But the Justice Department wants the appeals court to overturn the earlier ruling.

The government's appeal has delayed Mr Moussaoui's trial and a decision by the Virginia appeals court is not expected before Christmas.

Mr Moussaoui has been indicted on four counts of conspiracy to commit terrorism.

He was arrested on immigration charges three weeks before the suicide hijackings after he aroused suspicions at a flight school in Minnesota.

"What the defendant seeks is sort of a windfall from the ... government's war on terrorism" deputy solicitor general Paul Clement told the court on Wednesday.

National security

Federal prosecutors say al-Qaeda captives could reveal classified information if Mr Moussaoui were allowed to cross-examine them.

But he says they would testify that he is innocent.

The outcome of the appeal hearing could affect how other terrorism cases are handled, the government says.

Among those in US custody that Mr Moussaoui wants to call on his behalf are the former al-Qaeda operations chief Khalid Sheikh Mohammed.

Frank Dunham, one of Moussaoui's defence lawyers, told the BBC: "I think there's no way that he can defend himself without being able to obtain the evidence from these witnesses."

Unless the court can come up with a solution many experts say this case is heading to the US Supreme Court.

The BBC's Justin Webb, in Washington, says that if the government loses this appeal the entire case against Mr Moussaoui could be taken out of the civilian courts and moved to a military tribunal.

Last month, a judge revoked his right to represent himself at his trial after he repeatedly filed handwritten motions, some of which insulted the judge and prosecutors.