By Douglas Fraser, Scottish Political Editor
Sir Menzies Campbell, as chancellor of St Andrews University, was due to confer an honorary degree on Mohammed Khatami, the former Iranian president, on Tuesday.
But the Liberal Democrat leader will be at Westminster for a debate on Britain's continuing role in Iraq.
Sir Menzies has found that his new role as chancellor of the university is at odds with his political party role in arguing for human rights. Mr Khatami has denounced western civilisation and culture, censored arts and culture, and cracked down on student dissenters.
A senior party figure in the House of Lords has said Sir Menzies should be sure to distance himself from the Iranian's visit, as campaigners prepare to use his presence to highlight extensive human rights abuses in the country.
Lord Russell-Johnston, former Inverness MP and former president of the European Movement, said the visit and degree appear to be a response to a gift of books to the university. "Ming has only been chancellor for five or six months, so the decision may have been made before he became so, but every liberal should certainly distance themselves from this man."
The university has been sent a letter by parliamentarians detailing the president's involvement not only in human rights abuses but in limiting academic freedom.
The call for Sir Menzies to add his voice in opposition to the visit has come also from the Iranian opposition based in London.
Mahmoud Tabrizi, of the National Council of Resistance of Iran, said the LibDem leader's views on Iran "are too liberal and too appeasing. There is nothing this regime hasn't done to show that it is a fundamentalist, ruthless, and has been executing its opponents."
The letter asking St Andrews University principal Dr Brian Lang to cancel the visit has been circulated by Lord Corbett of Castle Vale, chairman of the British Parliamentary Committee for Iran Freedom.
It has been signed by 11 other members of the House of Lords, including Lord Russell-Johnston, Lord Waddington, a former Tory Home Secretary, Lord Fraser of Carmyllie, a former Lord Advocate in Scotland, and Baroness Harris, another LibDem peer.
As well as detailing Mr Khatami's central involvement in a "theocratic and brutal regime" that has seen 120,000 Iranians executed, and children used to clear minefields during the Iran-Iraq war, the letter focusses on its treatment of academic dissent. He was president from 1999 until last year.
"It is ironic that Khatami should be invited to a university with as rich a history as St Andrews, when during his presidency, the Iranian regime responded to the just demand of students for democracy and against repression by ordering vicious dawn attacks on university dormitories. Students were beaten using knives, chains and batons, resulting in a few fatalities. Some were even thrown out of first, second and third floor windows."
The protests this sparked resulted in thousands more students being arrested. Amnesty International claims some remain in prison, seven years on.
A spokeswoman for Sir Menzies said yesterday that he had no need to comment on the university's decision, as the role of chancellor was honorary. "He plays no role in the decision-taking process."
A university spokesman said: "We always recognised that Sir Menzies' duty as an MP and leader of his party took precedence over his duties as chancellor."