JOHANNESBURG, AUG. 11 -- Guards and strikers clashed at several mines today following a walkout by at least 230,000 blacks taking part in South Africa's biggest industrial work stoppage.

Union officials and management blamed each other for the violence.

Officials of the National Union of Mineworkers, which began the strike Sunday night at white-controlled gold and coal mines, said 14 miners were injured in clashes with guards late yesterday and 15 members of local strike committees were arrested.

{A mine manager said an unidentified 36-year-old man who had refused to join the strike was found murdered Tuesday in a possibly strike-related incident, United Press International reported.

{The manager, Bobby Jurd, said the man was found dead in his bed about 1 p.m. Tuesday at the idled Blinkpan colliery northeast of Johannesburg. "He was one of a small number of production workers who continued working despite the strike by almost the total work force," he said.}

Union General Secretary Cyril Ramaphosa told reporters the strike could spread to a gold processing plant, Rand Refinery, where South Africa's gold is turned into bars and where a strike ballot was scheduled today.

Union officials also reported violence and an unknown number of casualties at mines near Welkom, southwest of Johannesburg, where miners who refused to strike armed themselves with machetes and clashed with strikers.

Anglo American Corp., the giant mining company, accused the union of "disturbing incidents of intimidation" against nonstrikers at 10 mines.

The Chamber of Mines, an industry group, said there had been sporadic violence but that the mines were relatively calm.

The union said 340,000 workers in at least 44 mines were on strike, even though only 200,000 had been asked to stop work. The Chamber of Mines said up to 230,000 were on strike, seriously affecting 31 mines.

The union, the biggest in South Africa, demanded a 30 percent wage increase and danger pay. It vowed not to call off the action until it won.

Union spokesman Marcel Golding said the strike was approaching a turning point tonight when it would be 48 hours old, longer than previous miners' stoppages.

Black miners, who receive no strike pay, have been earning an average of $250 a month, roughly one-third as much as white miners, who did not strike. Management offered wage increases of up to 23.4 percent, which would narrow the pay gap between whites and blacks.