Liberty chief threatens to sue minister over Davis 'smears'

Culture Secretary Mr Burnham triggered the row last night by claiming that Mr Davis had shared "late night, handwringing, heart-melting phone calls" with Ms Chakrabarti as they opposed the Government's anti-terror plans.

The Evening Standard can reveal that Ms Chakrabarti has now written to Mr Burnham to declare that his remarks "debase" his ministerial office.

In her letter, the Liberty director demanded that he make a full public apology over his remarks or face a libel action.

Mr Davis yesterday quit his Parliamentary seat of Haltemprice and Howden in protest at Labour's erosion of civil liberties, from the use of CCTV and ID cards to 42-day detention without charge for terror suspects.

Both he and Ms Chakrabarti have led the attack against the Government, but Mr Burnham last night used a magazine interview to suggest that it was "curious" that the pair were in alliance given Mr Davis's Right-wing views on issues such as capital punishment.

Today, Ms Chakrabarti used her letter - which was copied to the Prime Minister and Attorney General - to hit back hard, claiming he had "set out to smear my dealings with the former shadow home secretary".

The Liberty chief, who has been married to her barrister husband for nearly 13 years, says that the minister's own behaviour is "curious ... coming as it does from a Cabinet minister; let alone someone with a partner and family of his own". She continued: "By your comments you debase not only a great office of state but the vital debate about fundamental rights and freedoms in this country. Indeed you seem reluctant to engage in that debate except in this tawdry fashion.

"I look forward to your written apology as I'm sure does Mrs Davis. If on the other hand you choose to continue down the path of innuendo and attempted character assassination, you will find that the privileged legal protection of the parliament chamber does not extend to slurs made in the wider public domain." She said the fruits of any legal action would go to Liberty.

Mr Burnham is said to be "aghast" at the suggestion that he was smearing the civil liberties chief. His spokeswoman said last night: "It was a lighthearted comment about the former shadow home secretary's political journey, by-election knockabout and nothing else."

But an alliance of women MPs across the political spectrum today rallied behind Ms Chakrabarti.

Labour MP Diane Abbott told the Standard: "I am extremely disappointed in Andy Burnham. I thought the Labour Party had left these sort of politics behind. He wouldn't talk like that if the head of Liberty was a man."

Tory MP Justine Greening added: "Shami has worked with MPs of all parties. She is completely driven but incredibly professional. What is really objectionable is that these were not off-the-cuff comments."