The US government will ask an appeals court to prevent the only person in the US charged over the September 11 attacks, Mr Zacarius Moussaoui, from calling witnesses currently detained at Guantanamo Bay on suspicion of being al-Qaeda members.
The prosecution case has been dogged by the issue after US authorities refused Mr Moussaoui access to the detainees on grounds of national security.
Prosecutors in Alexandria, Virginia, have notified the trial judge in Mr Moussaoui's case that they will appeal to a court based in Richmond.
The US government wants a ruling that they can refuse to make three al-Qaeda prisoners available to Mr Moussaoui, a French citizen, who has lived in Brixton, south London.
They have already defied two district court orders that gave the defendant the right to question the captives.
To sanction the government for its defiance, US District Judge Leonie Brinkema barred them from seeking the death penalty or presenting any evidence that could link Mr Moussaoui to the September 11th suicide hijackings.
If the government cannot restore its full prosecution case, it would be more likely the Bush administration would move the case to a military tribunal, where rules might be more favourable to prosecutors.
He is charged with participating in a broad al-Qaeda conspiracy to commit terrorism against the United States, including the September 11 attacks.
AP