The spy writer John Le Carré, the actors Colin Firth and Patrick Stewart, the novelist Iain Banks, fashion designer Vivienne Westwood and professor of philosophy A C Grayling are among a group of leading figures from the arts and academia who have written to Gordon Brown to oppose the extension of pre-charge detention to 42 days for terrorist suspects.
On the eve of a key vote on the second reading of the Counter-Terrorism Bill in the Commons, their open letter warns the Prime Minister that "community relations could suffer if the Muslim community appears to be ... targeted for prolonged pre-charge detention".
The result might "damage intelligence gathering and policing and ...efforts to engage with Muslims in the UK". They accused the Government of failing to produce a convincing case for undermining habeas corpus, the 800-year-old right which safeguarded people from arbitrary detention.
The Home Secretary, Jacqui Smith defended the measure yesterday and claimed that the Government could win the vote. But senior cabinet ministers have signalled to The Independent that there is likely to be tactical retreat during the Bill's later stages in the Commons to avoid a humiliating defeat for Mr Brown.
The Tories are not going to press for a vote tomorrow night on the second reading of the Bill, because there are other measures which they support. But the Tories will vote against the clause to extend detention without charge from 28 days to 42 days, along with the Liberal Democrats and a growing number of Labour rebels, leaving Ms Smith facing defeat.
Mr Brown promised to reach a consensus on the issue, and ministers privately admit they have failed to do so. "That hasn't happened," said one cabinet source.
Ministers are considering offering Parliament an earlier say in whether terrorist suspects should to be held without charge.
"Instead of seeking to further extend pre-charge detention, the Government should concentrate on prosecuting terrorism suspects through fair trials that meet international standards," said Amnesty.
Shami Chakrabarti, director of the civil rights group Liberty, said: "The fundamental issue is that the Government wants this power not for nightmare situations of genuine public emergency but for individual cases. Whilst it is likely that the Government will play with the description of those individual cases, that kind of semantic exercise is unlikely to satisfy principled critics."
Ms Smith told BBC1's The Andrew Marr Show: "I think we are getting a good response for the way in which we have gone about dealing with this. ...My responsibility is to do what I believe is necessary to protect this country from the serious, sustained, and in some ways growing threat from international terrorism."
David Davis, the shadow Home Secretary, said: "There is a consensus in the House of Commons for 28 days ...There [is] no evidence to show that we need more than 28 days."
He said Government arguments that one reason for needing an extension was the length of time it took to crack data on terrorist computers was "spurious".
Chris Huhne, the Liberal Democrat home affairs spokesman, accused Mr Brown and Ms Smith of "bashing their heads against a brick wall" on the 42-day question.