1,000 more agents in biggest peace-time expansion for MI5

David Blunkett will paint a grim picture this week of Britain still under imminent threat as he insists the state must have more power to deal with terrorists.

The Home Secretary is prepared to defy the Privy Council and risk a confrontation in the Commons rather than let go of his recently acquired power to detain foreign suspects indefinitely without charge.

Tomorrow he will announce that MI5, which guards against domestic subversives, is to undergo the biggest peace-time expansion in its 90-year history.

The organisation has been told it can recruit 1,000 more surveillance officers, linguists and technical staff, swelling its payroll by 50 per cent. Civil rights lawyers also fear that Mr Blunkett plans to rush ahead with legislation to make it easier for terrorist suspects to be convicted in British courts. He has hinted that he wants to alter the law so that terrorist suspects can be convicted "on the balance of probabilities" rather than the prosecution having to prove the case "beyond all reasonable doubt".

MPs will debate on Wednesday whether to retain the Anti-Terrorism Act rushed through Parliament after 11 September 2001. Part IV of this act has allowed Mr Blunkett to order the detention of 14 foreign suspects, who have no way of knowing how long they will be in prison.

The Government says they are too dangerous to be out on the streets, but can leave the country if they want to. The prisoners do not want to be returned to their countries of origin because they might be tortured or killed there.

Mr Blunkett's power to keep them in prison is due to expire in June because of a Privy Council ruling issued late last year. A committee of nine privy counsellors headed by a former leader of the Commons, Lord Newton of Braintree, said that indefinite detention of suspects should be ended "as a matter of urgency". But a Home Office spokeswoman said: "The public is entitled to expect that the Government will protect its right to life and liberty by doing everything possible to prevent terrorist attacks.

"The issue is how to protect public safety in the face of this threat. We believe that the renewal of the Part IV powers are important in helping to combat terrorism."

Mark Oaten, the Liberal Democrat spokesman on home affairs, said: "It's time for the Government to make up their minds. These individuals should either be charged or released. The Liberal Democrats will strongly resist any extension of the Home Secretary's temporary powers, and we seek to force a vote on it."

In reality, there is little prospect of Mr Blunkett being defeated in the Commons, though he may have a more difficult time in the Lords.

One rebel Labour MP, Robert Marshall-Andrews, said: "There will be at least a one-man Labour rebellion because I'll not vote for this, but I don't think there will be a very big Labour rebellion. I'm afraid that the parliamentary Labour Party and civil liberties long ago parted company."