Cameron and Clegg clash on Hunt row

The Liberal Democrat leader believes the independent adviser on Ministerial interests, Sir Alex Allan, should be brought in to consider the case.

The behind-the-scenes coalition clash emerged as Mr Clegg signalled that his MPs will abstain in a vote being forced by Labour on the issue today.

The Commons motion calls for Sir Alex to investigate whether Tory Mr Hunt misled Parliament and failed to take responsibility for his special adviser Adam Smith, who resigned after admitting his contacts with News Corporation had been too close.

The Lib Dem decision was said to have received “unanimous support” at a meeting of the parliamentary party last night.

Mr Clegg conveyed the news to Mr Cameron when they met later, a senior party source said.

“I don’t think the Prime Minister was pleased about it,” the source added. “The decision not to refer it to Sir Alex Allan was the Prime Minister’s decision, and we respect that.

“However, it is not a decision that is endorsed by the Liberal Democrats, therefore we don’t think we need to endorse it, therefore we won’t support it on the floor of the House.”

The source said Mr Clegg had discussed the matter with Mr Cameron on a number of occasions, and told him Mr Hunt should be subject to a probe.

Evidence of the coalition split will intensify pressure on the Prime Minister to call in Sir Alex for an independent assessment of whether the Ministerial code was breached. He is already facing accusations of double standards after triggering an investigation into Tory chairman Baroness Warsi, who has admitted failing to declare business links with a relative who accompanied her on an official trip to Pakistan.

A senior aide to Mr Cameron played down tensions with the Lib Dems, saying their decision was “not unexpected”.

Shadow culture secretary Harriet Harman said: “This is an important opportunity for the House of Commons to make clear the importance it places on secretaries of state being transparent and truthful to Parliament.”

Labour is unlikely to win the vote in the House, despite the Lib Dem abstention. Even if the motion was passed it would only be a symbolic blow to Mr Cameron, as he retains the final say over whether his independent adviser investigates.