JOHANNESBURG, AUG. 18 -- Striking black miners walked out of talks with South Africa's biggest mining company today after reports that police had again fired on strikers. The talks had been called in an effort to find ways of ending violence in the 10-day-old strike.

The National Union of Mineworkers said that policemen had fired birdshot, rubber bullets and tear-gas grenades at miners waiting to board taxis and buses outside a mine and then had beaten them with whips, injuring 15 men.

Cyril Ramaphosa, the union's general secretary, accused the giant Anglo American Corp., owner of the President Steyn Gold Mine in the Orange Free State, of complicity in an attack he described as part of a joint effort by government and management to break the strike, which has cut the country's gold and coal production by more than a third.

"We are dealing with a treacherous, cowardly and ruthless organization whose negotiations are based on deceit," Ramaphosa said of Anglo American, which has long considered itself one of South Africa's most progressive employers. "Our members are spilling their blood while we are sitting negotiating."

Anglo American denied any responsibility for the incident. A police spokesman in Pretoria said it had come about as the result of the miners' refusal to disperse when ordered to do so. The spokesman said a police patrol had fired rubber bullets and tear-gas grenades at a group of about 40 miners. No injuries were reported, he said.

Both Anglo American and the mine workers union left open the possibility of resuming negotiations on a series of proposals aimed at controlling the almost daily violence, which has caused one death and more than 300 injuries. Both sides have expressed fear that if the clashes continued to escalate they could sweep across all the country's mining fields and spread into many of its black ghetto townships, particularly those around Johannesburg.

Further clashes could come Wednesday if Anglo American carries out the announced closure of a coal mine and two shafts at separate gold mines as uneconomical, dismissing an estimated 4,000 of the striking miners.

The collapse of the talks on reducing violence would also have serious implications for ending the work stoppage, already the biggest and potentially the most damaging in South African history.

The mine workers are seeking a 30 percent across-the-board wage increase, but the mining companies offered, and then unilaterally implemented, raises of 15 percent to 23 percent. The companies say the pay issue is closed, but the union says it is the principal issue of the strike.