There are currently 10 such detainees being held in British prisons accused of terrorism offences.

They were arrested under the new Anti-Terrorism, Crime and Security Act which was introduced after the 11 September attacks on America last year.

Chakrabarti: "I have never been more embarrassed to be a lawyer"

However, their lawyers challenged the legality of indefinite detention, claiming it was against human rights.

In July, the Special Immigration Appeals Commission (SIAC) ruled that their detention was unlawful - but the government immediately appealed to the Court of Appeal.

And on Friday the Court of Appeal ruled the power to keep a suspect in prison without trial under the legislation was acceptable, providing the person was a threat to national security.

Human rights lawyer Shami Chakrabarti, condemned the ruling as an "embarrassment".

In a report published in September, Amnesty International attacked the power given to the home secretary, currently David Blunkett.

'Devoid of safeguards'

It said it was "inconsistent with the right to liberty and security" guaranteed in the European Convention for the Protection of Human Rights.

It also said the Act effectively created "a shadow criminal justice system" devoid of a number of crucial safeguards present in the ordinary criminal justice system.

Ms Chakrabarti, a lawyer for pressure group Liberty, told the BBC: "I have never been more embarrassed to be a lawyer or to stand in front of the royal courts of justice.

This allows the government to say that a British national is entitled to stand trial in a court of law but a foreigner can be interned indefinitely Shami Chakrabarti

"Last week the Lord Chief Justice gave an incredibly eloquent speech about the importance of the judiciary standing up to the government in difficult times.

"He said the temporary unpopularity of the judiciary was a price worth paying in defence of democracy and the rule of law.

"I'm afraid I don't think that promise was honoured today."

The judgment was a unanimous ruling by three law lords.

In a summary of the ruling, Lord Woolf, the Lord Chief Justice, said British nationals - who cannot be deported - were not in the same position as foreigners who could not be deported because of the risk of them being killed or otherwise persecuted.

National security

"Such foreign nationals do not have the right to remain in this country but only a right (for the time being) not to be removed for their own safety."

Lord Woolf said such differentiating on the basis of nationality was in accordance with international law.

He also admitted that in certain national security situations the government was better able than a court to make decisions about suspects.

"When doing so in the particular context in which this challenge arises, namely a state of public emergency, the court must also recognise that the executive is in a better position than a court to assess both the situation and the action which is necessary to address it."

The Home Office said: "The government's paramount responsibility is to ensure public safety and national security."

Appeal possible

But Ms Chakrabarti added she believed the "most horrifying aspect" was the ability to discriminate.

"This allows the government to say that a British national is entitled to stand trial in a court of law but a foreigner can be interned indefinitely," she added.

It is believed the detainees' lawyers will appeal to the House of Lords.

Lord Justice Brooke, in his contribution to the ruling, said an element of trust had to be placed in the authorities despite occasional mistakes.

"Unless one is willing to adopt a purist approach, saying that it is better that this country should be destroyed, together with the ideals it stands for, than that a single suspected terrorist should be detained without due process, it seems to me inevitable that the judiciary must be willing to put an appropriate degree of trust in the willingness and capacity of ministers and Parliament."