SOWETO, SOUTH AFRICA, AUG. 17 -- The African National Congress today accused sections of the state security services of promoting the bloody tribal battles in Soweto township as violence raged there for a second day.

Police used tear gas to try to prevent fresh clashes on streets where at least 31 people have been killed and 217 injured in two days. Factional fighting in Soweto and other townships during the past six days has left about 190 people dead.

The fighting in Soweto started Thursday after Zulu migrant workers attacked passengers in a train station and Xhosas, who are ANC supporters, retaliated.

In an impassioned statement, the ANC, the main anti-apartheid movement, accused sections of the state security services of instigating the fighting to weaken the ANC and divide blacks on tribal lines. Police deny this.

"Fighting amongst ourselves helps no one, save our enemies," it said of the violence.

"There is mounting evidence that the violence . . . is the result of a well-coordinated and orchestrated campaign to bring terror and internecine warfare into the {greater Johannesburg} region," the ANC added.

The ANC denied that the country's worst urban black-against-black violence was an ethnic struggle between Zulus and Xhosas. Although the ANC leadership and many of its members are Xhosas, the organization has tens of thousands of supporters who are from Zulu and other tribal backgrounds.

ANC Deputy President Nelson Mandela and President Frederik W. de Klerk held a meeting Thursday to discuss ways to end the feuding between mainly Xhosas and Zulu migrant workers loyal to the Inkatha Movement of Chief Mangosuthu Buthelezi.

Police in the Zondi, West Jabavu and Nancefield districts fired volleys of tear gas, trying to stop blacks chanting war cries from slashing and stabbing at each other with long knives, axes and spears.

Residents estimated that tens of thousands of Soweto's 2 million residents stayed at home, afraid of venturing into the streets. Many schools remained empty for a second day.

Helmeted riot police patrolling in armored cars were supported by white plainclothes officers carrying shotguns.

Police trying to convene emergency peace talks between local leaders of the warring factions said the meeting would not take place before Saturday. They gave no reason.