JOHANNESBURG, NOV. 17 -- South African police clashed with anti-apartheid activists for three hours here today as a campaign to force the collapse of all black township councils accelerated with marches and rallies around the country.

Riot police and army reinforcements, seeking to disperse groups of demonstrators, opened fire on them repeatedly with birdshot, tear gas and rubber bullets, and also used dogs. Protesters pelted police with bottles, stones and chunks of cement from buildings in a four-block downtown area.

Police said 15 people were injured, six of them seriously from gunshot wounds, in the worst outbreak of violence in the city since Feb. 2, the day President Frederik W. de Klerk announced the legalization of all anti-apartheid groups. One person thought to have been caught up in the confrontation died in the hospital, police said.

Two police vans were damaged by stones and gasoline bombs, and one white plainclothes officer was attacked by a small crowd but managed to escape, apparently without serious injury.

The street violence here was touched off by a local magistrate's last-minute rejection of a march request after the organizers had reportedly obtained permission from the Johannesburg town council and traffic police. Other marches in nearby Germiston and Cape Town, where permission was granted, took place without incident.

The march here was called to highlight the demand of local civic associations affiliated with the African National Congress for the resignation by the end of this month of all blacks serving on the governing councils in segregated townships. The ANC regards these councils, usually elected by a small percentage of residents and often corrupt, as "apartheid structures."

The government has denounced the "mass action" campaign as a violation of promises by the ANC to suspend its armed struggle against white rule and help end the political violence wracking this country.

However, ANC leader Nelson Mandela insisted repeatedly this week that mass action in the form of demonstrations, rallies and petitions is a part of democracy that the government will have to get used to. But he sidestepped questions about whether the campaign to abolish the town councils will encourage more violence.

About one-third of all such councils have already ceased to function, and the campaign to press the remaining council members into resigning gained a boost Thursday when the council in Atteridgeville, outside Pretoria, resigned.

Transvaal Province's director for local government, J.J. Van der Walt, denounced tactics used by activists to press council members into resigning. He said Friday that in one instance "25 petrol bombs were thrown at the house of one councilor," adding, "One may begin to understand the intolerable pressure brought to bear on these councilors."

Winnie Mandela, Nelson Mandela's wife, made a fiery speech at a funeral ceremony in Atteridgeville today in defense of mass action, saying the ANC intends to continue its campaign because it is the only way "to have our voice heard in the country."

"The government cannot teach us how to fight against them and how to fight apartheid," she said, referring to the official policy of racial separation.

The campaign by anti-apartheid groups against the township councils dates to the mid-1980s, when the kind of political activities now taking place here were illegal.

The campaign has been revived partly as a result of numerous conflicts between councils and residents over rent boycotts, squatter problems and a refusal to pay water and electricity bills as a form of protest.

But it also seems that the campaign is being used by the ANC to allow township activists to press for "alternative" local government organs, flex their political muscles and organize support generally for the ANC while the process of negotiations for a new constitution drags on.

Moses Mayikeso, a leader of the Civic Associations of the Southern Transvaal, said at a news conference today that the goal of the campaign is to replace the township councils with "democratic interim structures" to run local communities until the negotiations, expected to abolish apartheid, resolve the issue on a permanent basis.

"We are going to intensify the mass struggle until the councilors resign," he said.