TEHRAN (AFP) ― Iranian riot police fired tear gas and paintballs at anti-government protesters in Tehran, websites and witnesses said Monday, while an Iranian news agency said a bystander had been shot dead.

Fars news agency said a number of other people had been wounded by the gunfire and blamed the outlawed former rebel group, the People’s Mujahedeen of Iran.

Some opposition websites said that men on motorcycles had fired at the protesters.

Britain and the United State meanwhile appealed to the Iranian authorities to show restraint, recalling Iran’s earlier support for the uprising in Egypt.

U.S. Secretary of State Hillary Clinton hailed the “courage” and “aspirations” of the protesters and called on Iran to follow Egypt’s example and “open up.”

“We wish the opposition and the brave people in the streets across cities in Iran the same opportunity that they saw their Egyptian counterparts seize in the last week,” Clinton told reporters during a visit to the U.S. Congress.

Britain’s Foreign Secretary William Hague said: “President Ahmadinejad last Friday told the Egyptian people that they had the right to express their own views about their country.

“I call on the Iranian authorities to allow their own people the same right and to ensure that the security authorities exercise restraint.”

Police moved in when crowds of opposition supporters gathered in the capital’s Azadi (Freedom) Square began chanting “Death to the Dictator!“ ― a slogan used against President Mahmoud Ahmadinejad after disputed official results from a 2009 presidential election gave him a second term.

The website of opposition leader Mir Hossein Mousavi, kaleme.com, said that according to “unconfirmed reports, hundreds of protesters were arrested in Tehran.”

There was no immediate official confirmation.

The anti-government demonstrations, held despite a ban on rallies, were the first in Tehran since Feb. 11, 2010.

Opposition website Rahesabz.net said clashes were reported near Tehran University and on the road connecting Azadi Square with Enghelab Square.

Police had fired tear gas as protesters chanted “Ya Hossein, Mir Hossein” a slogan from 2009 in support of Mousavi, it said.

Rahesabz.net also reported chanting against supreme leader Ayatollah Ali Khamenei, with shouts of “Ben Ali, Mubarak, It’s your turn Syed Ali!” in reference to popular revolts that ousted Tunisia’s Zine El Abidine Ben Ali and Egypt’s Hosni Mubarak.

Websites and witnesses said thousands of opposition supporters had taken to the streets of Tehran in support of the Arab revolts despite a heavy police deployment.

Some set fire to rubbish bins while chanting slogans in apparent reference to Ahmadinejad.

Mobile phone services were cut and there were power blackouts in areas where the protests took place, witnesses said.

The authorities earlier surrounded the house of Mousavi to prevent him from attending the rally, which regime loyalists said was a cover for protests similar to those that shook the Islamic republic in 2009.

Fellow opposition leader Mehdi Karroubi has been under de facto house arrest, according to his website Sahamnews.org.

And Rahesabz.net reported that former reformist president turned opposition backer Mohammad Khatami’s house had also been cordoned off.

While Iran backed the uprisings in Tunisia and Egypt, the Interior Ministry banned the rally planned Monday by Mousavi and Karroubi.

Witnesses said motorbike-borne riot police armed with shotguns, tear gas, batons, paintball guns and fire extinguishers patrolled key squares to prevent the gatherings.

“Some policemen are chasing protesters in order to disperse them,” a witness said, describing the scene at Imam Hussein Square where he said there were around 1,000 riot police.

More police and Basij militiamen were in Haft-e Tir square, a regular site for anti-government protests in 2009.

Foreign media have been banned from on-the-spot reporting of the gatherings.

Later Monday, the state television website reported the protests had ended and that crowds of people had also demonstrated in support of the regime.

Mousavi and Karroubi and their supporters remain steadfast in rejecting Ahmadinejad’s presidency. They say the hardliner was re-elected through massive vote rigging in June 2009.

Their protests in the immediate aftermath of the election brought hundreds of thousands of people to the streets of Tehran and other cities, shaking the regime and dividing the nation’s elite clergy.

Iranian authorities crushed those demonstrations in a crackdown in which scores of people were killed and wounded, and thousands arrested. They blame groups such as PMOI and monarchists for the deaths during that unrest.