The Anti-Terrorism, Crime and Security Act enshrines a series of "bizarre, irrational and extraordinary" situations, a tribunal was told.

Human rights campaigners Liberty made the challenge over the indefinite detention of a group of terrorist suspects in Britain.

According to the Home Office, nine people are being held without trial under emergency legislation brought in after the 11 September attacks in the United States.

It (the legislation) is far broader than necessary to counter any threat to this country posed by al- Qaeda or its associates

Ben Emmerson QC

Ben Emmerson QC, counsel for several of the appellants, said the powers were "a disproportionate response", as the home secretary repeatedly insisted there was no immediate national threat.

He said the law was "discriminatory" as it only applied to holding foreign nationals and it was "intentional and overbroad" in who it affected.

This led to foreigners being unjustly treated whereas British nationals had "a fair trial or nothing", he added.

Rushed through

He said under the legislation Richard Reid, who was held in the United States after being discovered with a bomb in his shoe, would not have been detained.

The new legal panel called the Special Immigration Appeal Commission (SIAC) is looking at the legislation for the first time, after it was rushed through parliament last December.

The panel is made up of a Lord Justice, a High Court judge and an Appeal Court judge.

Mr Emerson said instead of tackling an urgent public emergency the laws served as "tough action" on particular immigrants and served as an effort to gain credibility with other states.

Another "major flaw" was that included in the legislation was the power to hold individuals who had nothing to do with al-Qaeda, or who did not pose a threat to the UK.

Threat

The tribunal was told the nine men being held were initially prevented from defending themselves as they had no legal aid or access to lawyers and were not told of what they were accused.

Mr Emerson said the laws were "nothing short of bizarre", allowing those suspected of terrorism to leave the country and plot terror acts outside the UK.

He said: "We say that these measures amount to an unprecedented and destructive interference with a range of personal and fundamental rights including the right to personal liberty and the right to a fair trial.

"We say that these measures cannot be rationally justified by any identifiable or imminent threat to national security."

Under the new legislation the authorities can intern without trial non-British citizens suspected of involvement in international terrorism and who they view as a threat to national security.

When the Act was passed in December the UK confirmed it was opting out of Article 5 of the European Convention on Human Rights, which guarantees the right to liberty and grants protection against detention without charge or trial.

That same month eight people were detained and held at a special ultra-high security unit at Belmarsh prison in south-east London.

Liberty says many of the original eight are still in detention, while four others have also been taken into detention since December.

All those detained are free to leave the UK at any time.

The hearing was adjourned until Thursday.