Some 1,667 people had been arrested as of early evening, according to the Royal Malaysia Police, with 16 children among them. Protest organizers said at a news conference earlier in the day that about 400 had been detained. By Saturday night, police said the crowds had been dispersed.

The government said the protest, organized by a loose coalition of opposition groups known as Bersih 2.0, was illegal. It had already declared Bersih an illegal organization and police said anyone found with Bersih-related materials, such as yellow T-shirts, could be arrested.

"Malaysians of all walks of life overcame the oppressive acts of the police to come out peacefully and in incredibly large numbers to show their love for their country and for the principles of justice," the coalition said on its website.

"We are nonetheless horrified that several hundred people have been detained, many of them without any justification whatsoever," it said.

Opposition leader Anwar Ibrahim was among hundreds of protesters who gathered at the Hilton hotel in Kuala Lumpur before heading toward the Sentral Station.

There the protesters breached police lines to march through the rail station, before being met by riot police with tear gas on the other side.

A similar demonstration called by the Bersih coalition in 2007 was broken up by police using water cannon and tear gas, local reports say.