Iranian police used batons to disperse dozens of opposition supporters chanting "death to the dictator" in downtown Tehran yesterday following the reported closure of a reformist newspaper, a witness said.

The latest street unrest after Iran's disputed June 12 presidential vote took place near the offices of the Etemad-e Melli newspaper of leading pro-reform cleric Mehdi Karoubi.

Mr Karoubi angered many hardliners last week by saying some arrested opposition protesters had been raped in jail. His party earlier yesterday said the daily had been temporarily shut down.

Even though the security forces have managed to quell the mass demonstrations that erupted after the vote, supporters of defeated moderate candidates have showed continued defiance by staging several smaller rallies over the last month.

The poll and its turbulent aftermath have plunged Iran into its biggest internal crisis since the 1979 Islamic revolution, exposing deepening divisions within its ruling elite and also further straining relations with the West.

The witness said he had seen police beat two young men who were in one of several smaller groups of protesters moving around in the streets near the Etemad-e Melli building, chanting anti-government slogans.

The witness, who declined to be named, also said he had seen one demonstrator being arrested and taken into a police car. The authorities say post-election street protests are illegal.

Earlier police prevented dozens of demonstrators from gathering outside the Etemad-e Melli offices, where the witness said he saw scores of police and police vehicles.

"They tried to gather in front of the building but police did not let them and asked them to leave," the witness said, adding protesters continued to chant "death to the dictator" and other slogans.

About 400 protesters later gathered a few hundred metres away, he said.

Mr Karoubi came fourth in the election, but he and the moderate runner-up, Mirhossein Mousavi, say it was rigged to secure hardline President Mahmoud Ahmadinejad's re-election. Mr Ahmadinejad and his allies deny it.

The website of Mr Karoubi's party, which is also called Etemad-e Melli (National Trust), said the newspaper was closed down late on Sunday on the orders of the prosecutor's office. The newspaper's managing editor, Mohammad-Javad Haqshenas, said he did not know whether it could be published again today.

The Isna news agency, citing Haqshenas, said the newspaper was targeted because it planned to publish a statement by Mr Karoubi on its frontpage yesterday. In the statement, carried by the party's website on Sunday, Mr Karoubi responded to "insults" against him by his hardline opponents and said he would not be silenced.

Iran arrested many hundreds of people after the vote during its worst street unrest since the revolution three decades ago.

At least 200 people remain in jail, including senior moderate politicians, activists, lawyers and journalists. Iran has this month staged three mass trials against detainees.

The authorities have rejected as "baseless" Mr Karoubi's allegations on August 9 that some detained protesters, both men and women, had been raped.