Gordon Brown’s case for holding terrorism suspects without charge for 42 days is bogus and little more than scaremongering, according to Sir John Major.

The former Conservative Prime Minister, writing in The Times today, said that Mr Brown’s security measures were more likely to encourage terrorist recruitment than defeat the extremist threat to Britain.

His remarks coincided with mounting concerns among antiterrorist police that concessions made to win Labour backbench support for the 42-day proposal had created a complex and almost unworkable scheme.

Police are also alarmed that the revised proposals for parliamentary scrutiny could compromise the security of an antiterrorist investigation at the height of an emergency. A senior source told The Times: “Some of what is being proposed amounts to a blurring of the lines between politics and operational policing.”

Mr Brown is facing his most serious parliamentary test when the vote takes place next Wednesday. It could be decided by the votes of the nine Democratic Unionists.

Yesterday’s criticisms will dent ministers’ confidence that amendments to the Counter-Terrorism Bill had put them on track to win next week’s key vote.

Sir John’s attack is one of his strongest criticisms of Labour since he left office after the general election defeat of 1997. He broadened his critique from the issue of 42 days to wage an all-out attack on Labour’s conduct of the War on Terror since 2001. Sir John said that ancient British rights were under threat from a government that embellished the case for going to war in Iraq, was complicit in the rendition of suspects to the American internment camp at Guantanamo Bay and presented the public with a misleading case for introducing compulsory ID cards.

He writes: “If we are seen to defend our own values in a manner that does violence to them, then we run the risk of losing those values. Even worse, if our own standards fall it will serve to recruit terrorists more effectively than their own propaganda could ever hope to do. The Government has introduced measures to protect against terror. These go beyond anything contemplated when Britain faced far more regular – and no less violent – assaults from the IRA. The justification of these has sometimes come close to scaremongering.”

Sir John cautioned against the creation by Labour of “an intrusive State with authoritarian tendencies”. He added: “This is not a United Kingdom I recognise and Parliament should not accept it.”

He was joined in his attack by the Church of England. A spokesman said: “We believe that a convincing case for the extension of the maximum period of detention without charge beyond 28 days has not been made out. This central point has not been addressed. We believe that any extension beyond 28 days will unacceptably disturb the balance between the liberty of the individual and the needs of national security.”

Sir Ken Macdonald, QC, who as Director of Public Prosecutions would have a key role in authorising extended periods of detention, said that he was not swayed by the Government’s amendments and repeated his view that the 42-day power was not needed.

But in an interview with The Spectator, Jacqui Smith, the Home Secretary, said:“I think if it was turned into a vote of confidence there would be massive support of the Government.”

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