TONY Blair suffered his darkest day as Prime Minister when MPs refused to back anti-terror laws he insisted were vital to protect the nation from further atrocities.

Forty-nine Labour MPs joined the Conservatives and Liberal Democrats in voting down plans to lock up terror suspects for 90 days without charge.

Among the rebels who inflicted Mr Blair's first Commons defeat were North-East MPs Chris Mullin (Sunderland South), Jim Cousins (Newcastle Central) and Doug Henderson (Newcastle North).

Frank Cook (Stockton North) did not vote because he chaired the committee scrutinizing the Terrorism Bill - and nor did Sunderland North MP Bill Etherington.

The vote - by a margin of 31 - left the Prime Minister gravely weakened after he had staked his authority on toughening up anti-terror laws after the London bombings.

A visibly tense Mr Blair was in the Commons chamber to hear the result of the vote, shaking his head as the defeat was revealed.

He had insisted only a detention period of 90 days would allow police to carry out complicated investigations and prevent further terror outrages. But he appeared to have misjudged the mood of backbenchers, many of whom said the measure would backfire by increasing resentment among Muslims.

MPs later voted by a majority of 33 for a rebel Labour amendment to allow detention for 28 days.

Unlike the crucial March 2003 vote to go to war in Iraq, Mr Blair had not threatened to resign if he was defeated on the Commons floor.

Instead, speaking at Downing Street after the vote, he said: "It is better sometimes to lose doing the right thing, than be doing the wrong thing."

His spokesman said the defeat had not threatened his personal position because he had tried to implement a request from anti-terrorist police for 90-day detention.

But many Labour MPs were openly questioning how long Mr Blair could survive with further battles ahead over education reforms, incapacity benefit and changes to the NHS.

And Tory leader Michael Howard said Mr Blair's authority was vanishing, adding: "This vote shows he is no longer able to carry his own party with him. He must now consider his position."

Earlier, Sharon Hodgson (Gates-head East and Washington West) was among Labour MPs who wrote to national newspapers insisting a vote against 90-day detention was a "dereliction of our duty as MPs".

Defeat came despite Mr Blair ordering Chancellor Gordon Brown back from Israel, Foreign Secretary Jack Straw back from Russia and party chairman Ian McCartney off his sick bed.

The Terrorism Bill, with the 28-day detention maximum, will clear the Commons today, before reaching the Lords, where it could still face a rough ride.

l After Mr Blair's defeat last night, bookmaker William Hill shortened the odds against him leaving office before the end of next year from 3-1 to 7-4. Hills also lengthened the odds against him beating Margaret Thatcher's record eleven-and-a-half years in office from 3-1 to 5-1.

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