By Jim Muir BBC Tehran correspondent

A leading figure in Iran's reformist movement, Abbas Abdi, has appeared in court in Tehran along with two other men, accused of gathering and selling information to foreign powers.

The men had been researching Iranian attitudes towards the US

Mr Abdi and his colleagues are directors of an opinion poll centre which carried out surveys of Iranian attitudes to the United States.

Dressed in prison uniforms and looking grim, Mr Abdi and the two other defendants listened as the prosecutor read out a lengthy indictment against one of them, Hossein Qazian, the head of the centre.

The charges include holding secret and unauthorised contacts with institutions and agents linked to foreign intelligence services, gathering and selling information to them and falsifying the results of opinion polls.

Advocate of dialogue

The attention of the hardline judiciary had been drawn to the polling organisations after one of them - which has also been shut down - reported that about three-quarters of those questioned were in favour of opening talks with the Americans on resuming relations.

Khatami has no power to intervene in such prosecutions by the judiciary

Ties between the two countries have been broken since 1979, when revolutionary students stormed the US embassy in Tehran.

Ironically, Mr Abdi was one of those who led the embassy takeover.

Now, like many others who took part, he is a leading advocate of dialogue with the US - a touchy subject for hardliners.

Mr Abdi's arrest a month ago stirred deep anger and concern among his fellow reformists who dominate Iran's Parliament.

One hundred and sixty MPs wrote to President Mohammad Khatami urging him to intervene.

He has asked his justice minister and others to investigate, though he has no power to intervene in such prosecutions by the judiciary, which reformists accuse of pursuing unfair partisan prosecutions with a hardline agenda.

'Unauthorised contacts'

The polling centre run by Mr Abdi and his associates made no secret of the fact that late last year it carried out research on behalf of the US-based Gallup organisation into Iranian attitudes to the US.

The charges also include having unauthorised contacts and meetings with someone described as an "intelligence agent" of the British embassy in Iran.

Embassy officials say they had been in touch with the polling organisation earlier this year with a view to conducting a survey on public attitudes to Britain.

But the project did not get under way.