SEOUL, JUNE 15 -- Thousands of South Koreans of varied ages and social classes gathered at Seoul's Myongdong Cathedral tonight for a candlelight mass that developed into an emotional new street protest against the government.

Worshipers who crowded the brick gothic cathedral applauded Cardinal Stephen Kim Sou Hwan, who, in his first sermon on the crisis, called on the government to reopen dialogue with the opposition. After the mass, thousands confronted police in nearby streets, many shouting antigovernment slogans.

Students fought with police at a university here and, according to reports from the provinces, in six other cities. Press reports said they burned seven riot control vehicles in the city of Taejon.

The new protest came hours after about 200 radicals who had taken refuge on the cathedral grounds were bused back to university campuses with an escort of priests, under a deal negotiated with police.

The government hoped that their departure would depoliticize the cathedral, which since Wednesday has been the focus of the most persistent street demonstrations and riots to confront the government of President Chun Doo Hwan. However the size and fervor of the turnout tonight suggested that the cathedral will remain a rallying point. And the diversity of the people attending offered new evidence that the movement is becoming more broadly based.

Nationwide, about 60,000 students joined rallies at 45 universities, according to the Korean news agency, Yonhap. Seoul's Yonsei University was the scene of a particularly violent riot that went on for hours this afternoon and evening, with students charging out the campus gates to hurl gasoline bombs at police lines.

At the cathedral, several supporters of the students cut their fingers to perform "blood-writing" on large sheets of paper, scrawling slogans such as "Drive Out the Americans." Anti-Americanism is a persistent but secondary theme among radical students. It seems to find no substantial support among the middle class, however.

The mass was said by Cardinal Kim, leader of South Korea's 1.5 million to 2 million Catholics and an influential critic of the government who has been conspicuously silent since the crisis began last Wednesday.

In a sermon, Kim told the people he expected the students who had departed to continue to fight for democracy. He called for new dialogue and for the government to reverse its April decision to suspend talks with the opposition on amending the constitution.

Kim praised the cooperation that allowed the students to leave without arrest. He told the more than 2,000 people who were packed inside that the government should extend this spirit of conciliation to other issues, such as freeing political prisoners.

Outside, several thousand people gathered in the cathedral grounds and an adjacent street, listening to the mass by loudspeaker. They included teen-agers in designer T-shirts, nuns, office workers and elderly people. A heavy thunderstorm broke out during the mass, but most people simply stood and got soaking wet.

On the street outside, hundreds of radical students confronted rows of riot police as the mass progressed. The students linked arms and pushed against police shields, driving them back half a block and chanting, "Down with military dictatorship."

When the mass ended, thousands of people lit candles and marched slowly from the church, singing a traditional Korean song entitled "Our Wish Is Unification." The police, however, blocked their way, apparently to prevent them from staging a march through the city. Jostling and chanting continued as the crowd was squeezed tightly. One small alleyway was left open to allow people to leave, however.

Late tonight, protesters were skirmishing with police in the area around the cathedral. In places, people were seen being wrestled into police vans and driven away.

Meanwhile, leaders from the government and opposition parties met today to discuss convening a special session of the National Assembly to discuss the crisis. There is talk of a face-to-face meeting between the head of the ruling party, Roh Tae Woo, and his counterparts in the three opposition parties.

It was not clear, however, what effect such action could have on ending the crisis. The demonstrators seem to be taking to the streets without leadership from the opposition party.

Chun, meanwhile, presided over a meeting of his National Security Council which included the chiefs of the three armed services, his intelligence director and the prime minister.