A lecture by an influential Islamic scholar considered the main thinker behind the reformist movement in Iran has been cancelled at short notice.

Abdolkarim Soroush was due to speak at Tehran's Amir Kabir University on Wednesday morning.

The official news agency quoted a statement by the university's Islamic Society of Students as saying the speech had been cancelled "because of what the university management described as security reasons".

The statement added that the lecture might take place next week.

Dr Soroush was a lecturer at Tehran University after the revolution. He promotes a "pluralistic" view of Islam and argues that Islam should not be turned into "an ideology with official interpreters".

'Dispair'

He has been prevented from teaching in Iran in recent years and taught at Harvard University for the past two years. He returned to Iran in July 2002.

He is a hate figure for the so-called "hezbollahi" vigilantes in Iran, who have often disrupted his lectures. Once, when he was due to speak at Amir Kabir University in the 1990s, the hezbollahis set up gallows outside the lecture hall.

Quoted by the reformist press, Dr Soroush told a students' meeting in Tehran on Tuesday that when President, Mohamed Khatami came to power society was carried forward by a wave of optimism.

"Now, however, a greater wave of despair has engulfed our younger generation. The current conditions are not desirable by any criteria and cannot be justified. Newspapers have been closed, there is poverty, corruption and unemployment, and the younger generation cannot easily digest this," he said.

He went on to say that official assurances were unconvincing.

"The president's promises have not been implemented either. Youths who were looking forward to the future, must now inevitably become disheartened," he said.

He told his audience that while they did not have "the power of a state to use force", they had other strengths.

"God has given you the power of thought, which your opponents and the faction opposed to the reforms lack," he said.

"You are society's body and this body must be strengthened. This will take time but you will definitely succeed in the future," he added.