The Government's majority was slashed to only 14 last night over the proposed introduction of house arrest.

A cross-party bid to ensure judges, rather than the Home Secretary, impose the orders on suspected terrorists was narrowly rejected by the Commons.

The Government's majority of 161 crumbled, with 267 to 253 opposing the proposed amendment to the Prevention of Terrorism Bill, which was spearheaded by Labour rebels and Liberal Democrats with Conservative backing, after a stormy six-hour debate.

It came despite fresh concessions by Home Secretary Charles Clarke, who said he would bow to pressure to allow a judge to be the first to decide whether control orders amounting to house arrest could be imposed.

But he also announced he would seek to give police the power to detain a suspect while the application to the judge was being decided.

The size of the revolt signals further problems ahead in the Lords, where without more concessions, the legislation faces possible defeat.

The result was the worst for Mr Blair since he saw his majority slashed to five on the second reading of the Higher Education Bill 13 months ago, which introduced top-up tuition fees.

MPs reacted angrily when news of the Home Secretary's concession emerged - as they would only go before the Lords for consideration.

Tory former Cabinet minister Kenneth Clarke was among the protestors, complaining that the decision to move amendments in the Lords rendered Commons consideration "a farce".

At the heart of opposition concerns was the Home Secretary's refusal to apply the proposed judicial procedure to all control orders, not just house arrest.

He insisted there was a "qualitative difference between deprivation of liberty" and the lesser control orders, such as restrictions on association with others and use of mobile phones".

Shadow Attorney General Dominic Grieve said control orders were "unpleasant, repellent and disgusting".

Former Foreign Secretary Robin Cook was also sceptical. He said the Home Secretary could still severely restrict liberty by deciding where a person worked, lived and travelled, and who they talked to.

Mr Clarke said he would consult on how long MPs will have to debate the measures when they return from the Lords. He said: "I do believe I have made very major and significant movement on the proposals."

Earlier, the Prime Minister warned on Radio 4 that there were "several hundred" people in the country believed to be engaged in plotting terrorist acts.

Labour MPs from the region who joined the rebel vote were Vera Baird (Redcar), Frank Cook (Stockton North), Jim Cousins (Newcastle-Upon-Tyne Central), and John Cummings (Easington).