Late concession on 42-day detention

Home Office minister Tony McNulty said he was optimistic "common sense will prevail" but signalled the fresh concession by suggesting that terror suspects who were eventually freed without charge could be paid compensation.

It would provide for any suspect held for more than the current 28 days and subsequently not charged to receive £3,000 for each extra day they were held in custody, the BBC reported.

Frantic last-ditch negotiations are continuing as Prime Minister Gordon Brown's anti-terrorism measures approach their moment of truth in a key Commons vote.

Wednesday night's vote remains on a knife-edge, with Labour rebels insisting their numbers were holding strong.

The DUP - whose nine MPs could swing the result - will meet on Wednesday morning to discuss their course of action. There has been speculation that they are on the verge of doing a deal to back the extension - which would almost certainly prevent a Government defeat.

Government whips were said to be offering potential rebels their "heart's desire" in return for supporting the controversial proposals.

They are rumoured to have promised one backbencher that ministers would make representations at the United Nations over easing sanctions against the left-wing Cuban regime.

Another has apparently been offered extra help for miners affected by lung diseases.

"It's basically your heart's desire," said one leading rebel. "The idea is that people can back down with honour."