Brazilian riot police have fired tear gas to break up a protest in support of the legalization of marijuana in South America's biggest city. Six people were detained.

A court ruled the Marijuana March in Sao Paulo was illegal. About 1,000 people still showed up for the rally Saturday in the city's financial heart, saying the march was for freedom of expression and not pro-marijuana.

Television images showed riot troops charging toward the protesters when they tried to march down the busy Paulista avenue. Some protesters said police shot rubber bullets at them but that could not be independently confirmed.

All those detained were later released.