London: An unofficial biography of Prime Minister David Cameron penned by former Conservative treasurer-turned-foe has caused a stir in the UK with revelations of alleged marijuana use and debauchery by him during his student days in Oxford University.

Lord Ashcroft, who donated millions to the party before falling out with Cameron, has co-authored "Call Me Dave", which makes a series of damming claims about the student days of Cameron.

UK PM David Cameron
UK PM David Cameron

The book claims that Cameron smoked marijuana and took part in bizarre initiation ceremony as part of a university society, called the Piers Gaveston Society.

The book also claims that Cameron once put his 'private part' into a dead pig's mouth during a ritual. Sources reveal that the story was described to the authors by a contemporary of the Prime Minister who went on to become an MP, in which he reportedly said the pig's head was resting on the lap of a member of a dining club at Oxford while Cameron carried out the act.

There are reports of photographic evidence of the alleged act. However, the individual who is said to own the picture did not respond to the authors. 

However, sources close to the British Prime Minister have denied that he was ever a member of the club in question during his time at the Oxford University.

"I am not intending to dignify this book by offering any comment. He (Ashcroft) has set out his reasons for writing it. The prime minister is focused on getting on with the job of running the country," Cameron's spokesperson said, in reference to Ashcroft's admission that he had a "beef" or grudge against Cameron for ignoring him for a major job in the previous government despite making a promise.

The book, co-written by journalist Isabel Oakeshott, is set for official release by the end of this month.

Ashcroft, a major Tory donor, was deputy chairman during Cameron's period as leader in Opposition.

In July 2010, the billionaire gave up his non-domiciled tax status to remain in the House of Lords after a law was passed requiring peers and MPs to be tax resident and domiciled in order to remain in Parliament.

The book claims that Cameron knew in 2009 that Ashcroft had "non dom" status and therefore did not pay UK tax on overseas earnings.

When the story broke in 2010, Cameron's spokesman has said that the Prime Minister had known about it only for a month, but the book says he was made aware the year before.