Security forces attacked and arrested pro-reform demonstrators gathering in Tehran on Sunday to mark the anniversary of the country’s 2009 disputed election, NBC News and Iran’s opposition website Sahamnews reported.

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

Ali Arouzi, a NBC News producer in Tehran, said he witnessed about 15 arrests and saw tens of thousands of pro-reform activists marching silently around the city.

Other witnesses said thousands of security personnel were deployed to stop any revival of anti-government protests that followed President Mahmoud Ahmadinejad’s re-election in 2009.

Opposition websites had called for a “silent rally” to mark the vote, which reformists say was rigged to secure the hardline president’s win. Authorities say the election was the most legitimate since Iran’s 1979 Islamic revolution .

Sahamnews also said supporters of the opposition gathered in other parts of the city.

“Shopkeepers were ordered to close down their shops … hundreds of people have gathered in other areas of Tehran,” the website said.