In a secret "dirt-digging" exercise, the party is mobilising its allies to trawl Whitehall for information that could discredit the Conservative leader.
An internal memo from Labour election strategists shows the party is organising a campaign to mobilise MPs and party allies to ask lists of potentially embarrassing questions about Mr Howard.
They include requests for documents about his cousin Simon Bakerman who was jailed in 2002 for his involvement in a pounds 20m drugs ring.
Last night, the Conservatives accused Labour of scrabbling "in the gutter" in a campaign of "character assassination" against the Tory leader. The party's co-chairman, Liam Fox, accused the Government of playing "political football" with the Act, and engaging in a "spiteful dirty tricks campaign".
He accused the Government of refusing to answer dozens of questions on policy that have been submitted by Tory MPs while using the Act for its own political ends. Mr Fox said: "It is becoming increasingly obvious Labour is launching a very spiteful dirty tricks campaign. Tony Blair has gone straight back to his old ways of spin and personal abuse. Instead of focusing on the issues that really matter to people, he appears determined to fight this election with smear.
"The Government should not be able to manipulate the law. It is releasing information it believes is damaging to opponents while refusing to answer questions about its own conduct."
News of the smear campaign came only days after Alan Milburn, Labour's election co-ordinator, was forced to withdraw two posters featuring Mr Howard which Jewish groups complained were anti-Semitic.
It also follows the revelation that Alastair Campbell, the Government's former communications supremo, has been given a role in the election campaign.
The confidential document, prepared by Labour election strategists, suggests questions should be asked implying Mr Howard may have abused his position as Home Secretary to fast-track a passport for the daughter of a family friend.
Lord Wyatt said his wife asked Mr Howard to help his daughter Petronella Wyatt, a journalist, obtain a passport swiftly, an allegation that Mr Howard has repeatedly denied.
They also planned to "tee up" gay activists over requests for papers relating to Mr Howard's role in drawing up Section 28, which the Tories introduced to ban local authorities from promoting a homosexual lifestyle.
The Tories accused the Government of hypocrisy following Mr Blair's previous criticism of personal attacks during election campaigns. In 1997, before the election, Mr Blair said: "Positive policies win elections, not negative campaigning."
Labour strategists have found that support for the Tories plummets when the role of Mr Howard is raised. The Government was accused of playing politics with the Act this week over the release of secret Treasury documents about the events of Black Wednesday when Britain crashed out of the Exchange Rate Mechanism. The Treasury is seeking approval from John Major and Lord Lamont of Berwick before agreeing to a request to publish papers relating to sterling's expulsion from the ERM on 16 September 1992.
But the Government has, so far, declined to answer 130 policy questions tabled by the Tories, including questions about communications between the Foreign Office and Gibraltar.
"Our requests are about present policy - all they can do is scrabble in the gutter for personal material over a decade old aimed at character assassination," said Julian Lewis, the shadow Cabinet Office minister.
Michael Ancram, the shadow Foreign Secretary, wrote to Jack Straw accusing him of refusing to release "embarrassing" information. "The Freedom of Information Act was not introduced so that you could hide your double- dealing shenanigans but so that the British public could see how the Government works," he said.
Yesterday, the Labour Party did not deny it was planning to use the Act to gather fodder for its election campaign.
"We haven't made any secret of the fact that we are going to use the Act to ask questions about the Tories," said a Labour spokesman. "They are all questions based on Michael Howard's record of Home Secretary."
The document shows Labour wanted to ask the former defence minister, Peter Kilfoyle, to ask questions about Mr Howard's cousin but Mr Kilfoyle said he had asked a general question about the early release of convicted drug dealers.Reuse content