The government of Gen. Augusto Pinochet severely restricted the right to assembly, shut down six opposition publications and put all other media under tight censorship today in the most sweeping crackdown since the aftermath of the 1973 military coup.

Decrees and military bans issued two days after the declaration of a state of siege banned all meetings in Santiago not explicitly authorized by military authorities except for those of churches, families and entertainment facilities.

"Legally constituted" organizations, which do not include political parties, are allowed to hold private meetings only after notifying officials five days in advance.

The government also ordered Chilean media not to report "any form of expression, whatever its origin, of political character, relevance or implication." Media are also banned from reports on terrorism or "acts that directly or indirectly could provoke public alarm."

The only opposition publication not closed down, the Christian Democratic weekly Hoy, was ordered to submit all of its material to the government authorities, who can take 48 hours to review it.

If fully implemented, the official measures would abruptly reverse six years of slow political liberalization and eliminate almost all peaceful means of opposition to military rule, said political leaders and human rights lawyers.

Officials have maintained that the crackdown is needed to combat a recent wave of terrorism that has included fatal bombings of police. However, today's measures appeared designed to dismantle the broad movement of political parties and labor unions that has led protests against President Pinochet for the past 18 months.

The Democratic Alliance, the centrist opposition political front, met throughout today to consider a response to the government, including a possible national strike. Its leaders said they hoped to conclude a long-delayed "constitutional pact" unifying centrist and leftist parties on a proposal for democracy.

However, party leaders, who were technically subject to arrest for meeting today, said they may now be forced to act clandestinely in seeking to organize protests or other activity. "The crackdown has disoriented us," said a centrist Radical Party leader. "We are going to have to relearn how to operate."

The first public demonstration against the government crackdown came today at the University of Chile's Engineering Faculty, where students gathered to protest the arrest of the faculty's student president and battled police who arrived at the scene. Church sources said at least 35 protesters were arrested and one student was shot in the head with buckshot.

In selective raids on political offices and homes, secret police arrested at least 49 political and labor activists in Santiago and the southern city of Temuco by late today, according to human rights organizations. However, lawyers for the groups said authorities had refused to acknowledge any detentions.

In a midday press conference reported only by foreign media, Democratic Alliance President Ricardo Lagos described the government's shift of policy as "an intention to take the situation back to September 11, 1973," the day of the military's coup against socialist president Salvador Allende.

"The Pinochet government thinks it can resolve its crisis with repression," said Lagos. Pinochet "is involving the armed forces in an extraordinarily dangerous course. Force will not impede discontent, nor will it solve the real and profound problems of Chilean society."

In contrast, Interior Minister Sergio Onofre Jarpa maintained today that "there has not been a retreat in the transition to democracy. What there has been is an obstacle that blocks the advance," which he defined as an attempt by "terrorists" to "impose a totalitarian dictatorship."

The government actions, Jarpa added, "don't have the objective of persecuting anyone." Pinochet, he said, "is taking measures through the state of siege to prevent subversives from succeeding in transforming the life of the country."

Jarpa's continued role in the government after the reversal of his dramatic resignation Monday has been seized on by Chile's traditional political right as an assurance that Pinochet has not abandoned his commitment to a transition to limited democracy in 1989.

In a series of public statements before today's media blackout, jittery conservative leaders stressed that the political liberalization led by Jarpa since August 1983 must continue. The right-wing daily El Mercurio said editorially that government repression should be carried out "without restricting the legitimate areas of liberty that the transition has been sanctioning."