JOHANNESBURG, AUG. 15 -- Security guards fired rubber bullets at rock-throwing black miners, injuring six, and seized homemade weapons today at one of dozens of strike-bound South African mines, a company spokesman said.

Witnesses said that after the clash at Matla colliery east of Johannesburg groups of strikers chanted, "Viva ANC," referring to the outlawed African National Congress guerrilla movement fighting to end white domination in South Africa.

More than 220 miners have been injured since 300,000 gold and coal miners stopped work last Sunday in the country's biggest industrial showdown with white-run companies.

A spokesman for the Trans Natal Coal Corp., which owns Matla, said the fighting broke out when security guards investigated reports that strikers had stockpiled weapons at a miners' hostel.

Yesterday, more than 100 workers were hurt in the most serious violence since the strike was launched by the National Union of Mineworkers, the country's biggest union.

Mine union spokesman Marcel Golding said today 63 persons were arrested after a clash in which 76 were injured yesterday at the Western Deep Levels gold mine west of Johannesburg. During the fighting police fired rubber bullets at machete-wielding miners.

Another 27 miners were hurt yesterday at a colliery at Middleburg, east of Johannesburg.

Spokesmen for the Chamber of Mines, which includes six of the mining companies hit by the strike, said today they were not going to make any new wage offers to the union, which is seeking a 30 percent increase. The mining companies have offered increases of between 15 and 23.4 percent.

The chamber said it was prepared to negotiate other issues such as death benefits. But Golding told reporters the union was interested in talking only about the entire package of disputed issues, including wages and danger pay.

The strike has seriously hit production in half of South Africa's gold- and a fifth of its coal mines.