TEHRAN Iranian riot police on motorcycles beat supporters of presidential challenger Mirhossein Mousavi who were protesting on Saturday against President Mahmoud Ahmadinejad's disputed election win.
A Reuters reporter said she and others were beaten by police with batons as police chased and arrested demonstrators staging a sit-in at Tehran's Vanak Square, one of the capital's busiest intersections.
At least three people were injured in the clash, which broke out after the Interior Ministry announced the hardline incumbent's resounding victory in Friday's vote.
Mousavi, a moderate, protested against what he called violations and vote-rigging during the election. Interior Ministry officials rejected the allegations.
He said in a separate statement that members of his election headquarters had been beaten "with batons, wooden sticks and electrical rods."
Tehran's deputy police chief, Mohsen Khancharli, said the force would "strongly confront" any gathering or rally held without permission. He said people protesting against the election outcome had damaged cars.
"Police are not confronting people but only those who are disturbing public order or who make damage to public places," he told the official IRNA news agency.
Up to 2,000 Mousavi supporters took part in the sit-in in the middle of the road, chanting: "Mousavi take back our vote! What happened to our vote?."
Hundreds of the former prime minister's backers later gathered in side streets near Vanak, chanting anti-Ahmadinejad slogans and bringing traffic to a standstill. "We are Iranians too," and "Mousavi is our president," they shouted.
The protests were a first reaction by Mousavi's supporters, who thronged the streets of Tehran nightly in the run-up to Friday's vote, to Ahmadinejad's victory.
Some demonstrators set rubbish bins on fire and taunted riot police. Others threw stones at them. Police charged at the protesters who then fled, only to return shortly afterwards.
"The election was corrupt. If Ahmadinejad had won where are his supporters? How come they are not celebrating? said Reza, 25. "Most people think Mousavi won the election," said another young man, Saman. They gave only their first names.
Clashes between police and Mousavi supporters also took place in other areas of the capital, witnesses said. Reuters photographs showed a burning bus in downtown Tehran, as well as motorbikes on fire. Elsewhere in Tehran, tires were set ablaze, witnesses said.
Scuffles also broke out early on Saturday between police and chanting Mousavi supporters in another Tehran square.
Police say they have increased security across the capital to prevent trouble. Iran's Supreme Leader Ayatollah Ali Khamenei urged defeated presidential election candidates to avoid provocations and to support Ahmadinejad.
(Additional reporting by Parisa Hafezi; editing by Janet Lawrence)