Ministers are preparing limited concessions to Labour rebels over plans to hold terror suspects for up to 42 days without charge.
But Gordon Brown has warned Labour opponents that he will press ahead with the contentious anti-terrorism measures even if it means suffering a Commons defeat.
Tony McNulty, the Police minister, said he was prepared to talk about enhancing the role of Parliament in authorising any decision to hold terror suspects for more than the current 28-day limit. He told MPs scrutinising the Counter-Terrorism Bill that he would consider proposals to allow the Commons to vote on the powers within seven days of detention being approved. Under current plans MPs might have to wait 30 days before voting on such a move.
Mr McNulty lambasted opponents who denounced the detention plans as a form of internment. He said: "This is a woefully irresponsible, intellectually sloppy and downright fallacious description."
Labour rebels believe Mr Brown's concessions over the 10p tax row will embolden critics of the counter-terrorism proposals. Austin Mitchell, the Labour left-winger, told the ePolitix.com website: "They had to give in to the rebels and they will do so again on the 42-day detention move. It is silly for the Government to produce things that will create that kind of reaction among backbenchers."
Senior ministers insist they will not back down, despite public statements by the Director of Public Prosecutions Sir Ken Macdonald that extending the current 28-day limit on detention is unnecessary.
Ministers believe some Tory MPs may defy David Cameron to bolster the Government when the Commons votes on the 42-day issue next month. Government whips have allowed two days for debate on the report stage of the Bill's progress. But the date of the debate has been put back, amid fears of a major rebellion.