Home Secretary David Blunkett is considering his grounds for appeal after the government's anti-terrorism law was branded "discriminatory".

The Special Immigration Appeals Commission (SIAC) ruled on Tuesday that the law used to detain nine alleged international terrorists without trial breached the European Convention on Human Rights.

It said the law was discriminatory because it applied only to foreign nationals.

I think the public will have no difficulty in understanding why we are dealing differently with foreign nationals

Beverley Hughes Home Office Minister

The suspects, who were arrested under emergency powers introduced in the wake of September 11, will now appeal against their detention.

The SIAC will hear their appeals. The hearings are expected to be held on 7 October.

They will not be released for the time being because of the Home Office appeal against the tribunal's ruling.

Home Office Minister Beverley Hughes defended the emergency legislation.

She said the law had always distinguished between British citizens and foreign nationals.

"I think the public will have no difficulty in understanding why we are dealing differently with foreign nationals," she said.

"We have had a law in this country for 30 years which gives the government the power to deport a foreign national not conducive to the public good.

"I don't think the judges seem to have understood that in taking the powers in the emergency legislation we have simply extended that existing provision in relation to foreign nationals in the light of the public emergency facing us."

She added that the government had evidence that the nine posed a threat but could not deport them because there were fears for their safety in their home countries.

David Blunkett brought in emergency powers

A Liberal Democrat peer predicted the government could face "humiliation" on the international stage if the European courts upheld the SIAC decision.

Lord Lester of Herne Hill, a member of the joint committee on human rights, said the home secretary should instead seek to introduce new legislation to "fill the gap" created by the ruling.

The court's 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.

Shadow home secretary Oliver Letwin said: "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."

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".

Free

The director of civil rights group Liberty, John Wadham, 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.