Thousands demonstrate silently in Tehran

TEHRAN, Iran (CNN) - About 5,000 protesters marched slowly and silently through Tehran on Sunday near a mosque where the government was allowing a demonstration for the first time in days.

A witness told CNN that opposition leader Mir Hossein Moussavi made an appearance at the Ghoba mosque Sunday afternoon, waving to the crowd from the windows of his car. The witness was unable to make it through the crowd into the mosque, however, and was uncertain whether Moussavi - a former prime minister who had a permit to speak at a ceremony honoring a hero of the 1979 Islamic Revolution - addressed the gathering.

Authorities rode motorcycles alongside the marchers, who tried to walk slowly and drag their feet. Police beat their batons on their shields to keep them moving, but some demonstrators told officers that they had the legal right to protest in peace.

Demonstrators were still pouring off side streets to join the march at 7:30 p.m. (11 a.m. ET). At least one man was arrested during the protest by green-uniformed police in riot gear, who beat him with batons before taking him into custody.

There was heavy police presence outside the mosque, and members of the government-backed paramilitary Basij force watched the crowd and videotaped protesters from a nearby rooftop as evening set in.