Terror suspects should not be held without charge beyond the current limit of 28 days, MPs and peers have said.
The Joint Committee on Human Rights (JCHR) rejected increasing pre-trial detention without proof that the current period is inadequate.
"A power with such a significant impact on liberty as the proposed power to detain without charge for more than 28 days should, in our view, be justified by clear evidence that the need for such a power already exists, not by precautionary arguments that such a need may arise at some time in the future," its report warned.
The JCHR recommended stronger judicial safeguards and a full adversarial hearing when deciding if further pre-charge detention is needed.
Last week, Prime Minister Gordon Brown said there would be consultation over doubling the current limit to 56 days. The issue triggered Tony Blair's first Commons defeat in 2005 when he tried to extend the limit to 90.
Andrew Dismore, the committee's Labour chairman, demanded: "Where is the supporting evidence to extend the detention period? As far as we've heard there has not yet been a case where 28-days was inadequate."
The JCHR also said it favours the use of intercept evidence in court which it believes will help bring more prosecutions against terrorists.
And it urged ministers to consider innovations such as post-charge questioning in a bid to reduce the need to extend detention.
A Home Office spokesman said: "The Prime Minister has announced that the Government will consult on the issue of pre-charge detention as there is a growing weight of opinion that it may be necessary to extend the 28-day limit.
"The Government will be discussing this with colleagues and hopes to achieve a consensus before coming to a decision."
I am glad to know that both MPs and peers are firmly opposed to McStalin turning Britain into a national gulag for Muslims and opponents the Nulab tyranny.