An Oxford don was drawn into the the race for the White House in a murky plot to embarrass Barack Obama days before the US presidential election.

Dr Peter Millican, a philosophy don at Hertford College, was asked to “prove” links between Democrat Party presidential candidate Barack Obama and a former terrorist, using software he created to compare texts.

His programme, Signature, can analyse writing styles and indicate if they were the work of the same author.

Dr Millican was contacted by US businessman Robert Fox and offered US$10,000 (£6,200) to compare two books – one written by MR Obama and another by ex-terrorist William Ayers.

Mr Fox asked Dr Millican to prove a theory put forward by American writer Jack Cashill that Mr Ayers had ghost-written Mr Obama’s memoir Dreams from My Father.

Ahead of Tuesday’s US presidential election, the rival Republicans have accused Mr Obama of “palling around” with Mr Ayers, who co-founded the Weathermen, a radical 1960s group that bombed US government buildings in Washington and New York.

Dr Millican said he was asked to compare Mr Obama’s memoir with Mr Ayers’ memoir Fugitive Days.

He said his software had already been used to try to prove Mr Obama had lied about writing the book, but the tests were “inadequate”.

He said: “At the point they approached me I looked at the tests they had done. I felt their tests proved nothing and they seemed to be pretty poor.”

The 50-year-old said he was told a press conference had been arranged in Washington where it was planned that analyists who supported the claim would expose Obama’s alleged deceit.

Dr Millican said “I felt it was extremely unlikely that it would be true, and very unlikely if it were true that it would be provable.

“I thought it would be better to have some objective input into the process and hopefully persuade them it was not a goer.

“Obama is a very impressive man. If the allegations were true, then he is not the man I think him to be.”

Contracts were due to be signed last week, but the Americans’ interest allegedly waned after Oxford University insisted the research should be put in the public domain regardless of what the results were.

Dr Millican said: “I’m not accusing any of the people I talked to of any bad faith. They were sincere but misguided.

“They were genuinely confident that they had strong evidence and I was very confident they didn’t.”

For details on Signature, go to www.philocomp.net