Iranian security officials have used baton charges and tear gas to disperse hundreds of protesters at a silent rally in central Tehran marking the second anniversary of the country's disputed presidential election.

Riot police and plainclothes basij militia were deployed in various locations in the capital, arresting at least tens of protesters.

Supporters of the opposition green movement marched in groups along Vali-e-Asr street – the city's main commercial thoroughfare and a rallying point for protesters in recent years.

A protester told the Guardian that demonstrators mainly marched on the pavement, and – as requested by the organisers – did not shout any anti-regime slogans.

"People were pretending that they were in the streets for a walk but it was obvious that they were out in protest to mark the rigged election in 2009," he said.

"They were silent but their numbers were ten times more than an ordinary day in Vali-e-Asr street, I think around 30,000 people were out there in total," the protester said in a phone interview from Tehran.

Kaleme, the website of the opposition leader Mir Hossein Mousavi, said that protesters clashed with riot police near Saei Park in Vali-e-Asr and Sahamnews, the website of Mehdi Karroubi, another leader of the opposition, said the police attacked people with electric batons.

Mousavi and Karroubi have been placed under house arrest since mid-February when they called for street protest in solidarity with the Arab uprisings.

"Security forces attacked the crowd with electric batons ... in the Vali-e Asr street to disperse the demonstrators," Sahamnews said.

"Shopkeepers were ordered to close their shops … hundreds of people have gathered in other areas of Tehran," the website added.

Another protester told the Guardian: "The riot police panicked and although people were silent, they arrested people without any charge or suspicion just to intimidate them."

The protester continued: "Plain-clothes basijis were riding past on fast motorbikes to spread panic among protesters."

News of the protests came as it emerged that a leading journalist and opposition figure had died of a heart attack after spending 10 days on hunger strike in Tehran's notorious Evin prison.

Hoda Saber, a 52-year-old political activist from the opposition Nationalist-Religious movement, was taken to the Modarres hospital in the city after a cardiac complication, which his wife claims was brought on by his hunger strike.

Speaking from Tehran, Saber's wife, Farideh Jamshidi, told the Guardian: "My husband died two days ago, but we were unaware of his death until today when someone in the hospital informed one of our friends."

She said Saber stopped eating food and later stopped drinking water in protest at the death of his fellow dissident Haleh Sahabi, She died of a heart attack during scuffles with security forces at the funeral of her father, Ezatollah Sahabi, the leader of the Nationalist-Religious alliance of politicians, on 1 June.

Several human rights organisations have issued statements coinciding with the anniversary of the election and many have expressed concerns for those political prisoners arrested since 2009.

The foreign secretary, William Hague, also issued a statement, saying: "Two years after people took to the streets to demand reform, I want it to be known that our attention has not been diverted and we will continue to call on Iran to implement its international human rights obligations."