David Blunkett's anti-terrorism legislation has come under fire from a committee of MPs and peers.

In a report released on Wednesday, parliament's joint committee on human rights found that Britain risks breaching key international obligations by persisting with the Anti-terrorism, Crime and Security Act 2001.

The law, introduced by the home secretary in the wake of the September 11 attacks on New York and Washington, allows for the indefinite detention of suspects without trial, who can only be represented by lawyers appointed by a government minister.

The MPs and peers said Blunkett must reform the law "as a matter of urgency".

They concluded that the UK risks "being in breach of its obligations under the Convention Against Torture if the Special Immigration Appeals Commission (SIAC) or any other court were to admit evidence which has been obtained by torture".

They added that they were concerned at "the adequacy of the safeguards against injustice in the SIAC process, in light of the fact that one individual was detained without charge for fifteen months before the error in authorising his detention was established".

And the report criticised "the fact that special advocates are appointed by the attorney general, who has personally represented the government before the SIAC, and the rigidity of the rule prohibiting any contact between the detainee and the special advocate".

Concern was also expressed at "discrimination inherent in a measure which targets only non-nationals, and the disproportionate impact of the use of Terrorism Act powers on the Muslim community".

The report recommended "the use of more intense overt surveillance, subject to safeguards".

On human rights grounds it said this would be "preferable to indefinite detention because it is less restrictive of liberty".

The parliamentarians also said they were "not persuaded" by Blunkett's suggestion that a new criminal offence of acts preparatory to terrorism, likely to be introduced in the autumn, "would facilitate prosecutions which are not currently possible".

"No other country in the world has derogated from its international human rights obligations, and no other country apart from the USA has resorted to indefinite administrative detention," the report concluded.

"The experience of other countries suggests that it must be possible to deal with the threat from terrorism by means of criminal prosecution."