Britain's House of Commons has approved a plan to extend the period of time terrorism suspects can be held without charge, in a vote seen as a major test for prime minister Gordon Brown.
Parliament voted 315 to 306 in favour of extending the pre-charge detention time limit to 42 days from 28 days, showing opposition within Mr Brown's party had slashed the Labour government's majority to nine votes.
Defeat would have been damaging for Brown at a time when his poll ratings are at record lows and some Labour lawmakers are openly questioning his suitability to lead the party into a general election due by May 2010.
Up to 30 Labour MPs were earlier reported to be against the proposal. Defeat would have been humiliating for Mr Brown and seriously undermine his leadership, dented by poor election results, a slowing economy and poll ratings at an all-time low.
The government wants to extend the maximum time police can hold and question terrorism suspects before having to charge or release them to 42 from 28 days. It says the measure would be used only for "grave and exceptional terrorist threats".
Victory gives Mr Brown, who has a majority of 65 in the House of Commons, much-needed breathing space but a significant Labour revolt would have left the government dependent on support from minority parties.
Attempts by former prime minister Tony Blair to extend the detention limit to 90 days in 2005 ended in failure, dealing Mr Brown's predecessor his first parliamentary defeat as prime minister.
Opponents of the bill say it is an infringement of civil liberties and a threat to police attempts to win "hearts and minds" in the fight against terrorism. They say most other countries have detention periods shorter than 28 days.
Elections for local councils and a single parliamentary seat in May showed a swing to the opposition Conservative Party that would hand it a landslide if repeated at the next election.
"What we have is the worst of all worlds: a symbolic assault on liberty which is unnecessary, a change in the law which is counterproductive and a procedure which is unworkable," said Conservative home affairs spokesman David Davis.
"We do not defend our liberties by sacrificing our liberties," he said.
Critics said the bill would undermine police attempts to win "hearts and minds" in the fight against terrorism and that most other countries had detention periods shorter than 28 days.
Mr Brown is grappling with an economic slowdown, public anger over rising fuel and food costs, anxiety over a housing market slump and widespread frustration with an 11-year-old government. A YouGov poll published in the Daily Telegraph showed 69 per cent of Britons supported the extension of the detention period.