LONDON • A new biography on Mr David Cameron, Call Me Dave, by a former ally contains claims of youthful debauchery by the future British leader, according to extracts published by the Daily Mail.

Reactions on social media over the last two days focused on the description of a bizarre initiation ritual for an Oxford University club made by an unnamed contemporary of Mr Cameron's who is himself an MP. The lawmaker claimed that the ceremony involved a dead pig and that Mr Cameron "inserted a private part of his anatomy into the animal's mouth".

Mr Cameron on Monday refused to "dignify" the book's allegations by commenting. But this did not stop political rivals using the furore to poke fun at him. The hashtag #Piggate quickly topped Twitter trending in Britain, with users making many pig-related puns.

Downing Street declined to comment on the claims, which were repeated in other British newspapers.

The book is being published by billionaire Michael Ashcroft, a major donor to Mr Cameron's Conservative Party who turned against him when he was not appointed to a senior government role.

Mr Ashcroft, a former deputy chairman and treasurer of the party, admitted that he had been expecting the ministerial appointment following Mr Cameron's first general election victory in 2010.

The book also claims that Mr Cameron smoked marijuana at university. Asked in the past about any drug-taking, he had said that he had "a normal university experience".

The Daily Mail said that the biography would "make political waves" but the Guardian's media columnist Roy Greenslade said that "it is highly doubtful that the book will cause more than a ripple".

The Independent said that "perhaps most damaging politically" is the claim by Mr Ashcroft that Mr Cameron knew of his non-domiciled tax status in 2009. Mr Ashcroft's status, which meant he did not have to pay UK taxes on overseas earnings, caused a major scandal at the time. Mr Cameron's office said the prime minister had found out only in 2010.

AGENCE FRANCE-PRESSE