Nine foreign terrorist suspects arrested in the UK in the wake of the 11 September attacks have won an appeal against being held without trial.

The suspects were held under emergency powers brought in by Home Secretary David Blunkett - and their success on Tuesday is seen as a blow to the government's legislation.

David Blunkett brought in emergency powers

The Special Immigration Appeals Commission (SIAC) ruled that their detention was unlawful.

But the nine men are unlikely to be released as the government is to go to the Court of Appeal to challenge the decision.

The decision has been welcomed by human rights pressure groups.

Opposition MPs say that they had warned that the anti-terror laws were likely to be challenged.

Committee chairman Mr Justice Collins said the government's Anti-Terrorism, Crime and Security Act, rushed through in December, was "not only discriminatory and so unlawful ... But also it is disproportionate".

The law was unfair because it allowed the detention of foreign nationals only, although British citizens may have been equally involved with al Qaeda or other terrorist organisations.

It breached the European Convention on Human Rights under the Human Rights Act, he said.

The UK opted out of Article 5 of the Convention, which gives protection against detention without charge or trial to introduce the law.

In a statement the Home Office insisted that the finding did not make the detention unlawful.

"The individuals will not be released as a result of this judgement", it said.

Free to leave

The Home Office was disappointed that the court had found these powers discriminated against foreign nationals but UK law had always distinguished between UK citizens and foreign nationals.

Detainees were free to leave the UK voluntarily, it said.

"The Home Secretary has used his powers to detain these individuals on the basis of detailed and compelling evidence.

"We believe that the individual appeals would have been heard sooner but for this challenge," it continued.

But shadow home secretary Oliver Letwin said this was exactly the type of legal problem he had warned about.

"I continue to believe that we shall have to find a way of making it legal to repatriate some of these individuals, instead of trying to detain them in the United Kingdom," he said.

Liberal Democrat home affairs spokesman Simon Hughes said he hoped the government accepted the ruling which was a "great embarrassment and the strongest rebuke for the Home Secretary".

Human rights pressure groups have welcomed the decision.

John Wadham, director of civil rights group Liberty, said it was a "manifestly unjust and discriminatory" power.

A spokesman for Amnesty International said those now being held under the laws must be charged or set free.

Under the anti-terrorism act, foreign nationals can be detained in the UK when it is not possible for them to be deported.

Eleven people were held under the legislation but two have now left Britain.

Seven have been held in Belmarsh high security prison, in London, for nearly seven months.

Secret evidence

Their lawyers say they are locked up there for 20 hours a day.

They told the SIAC earlier this month that the Act created a series of "bizarre, irrational and extraordinary" situations depriving detainees of their legal and human rights.

It was the first time that the specially-appointed panel had examined the legality of the anti-terrorism legislation.

The panel heard the case in public for three days this month before continuing in a secret session.

A "special advocate" appointed by the Attorney General and vetted by MI5 and MI6 examined evidence deemed too secret for the suspects or their lawyers to see.

Solicitor Natalia Garcia, who represents two of the detainees, said they would be delighted.

"However, there is no immediate prospect of their release," she added.

They would now begin preparing for the Court of Appeal hearing expected on 7 October, she said.