A period of outspoken dissent, provoking harsh suppression by the military junta, appears to be building on the momentum created by tense encounters between the government and labor on May Day.

Followers of President Augusto Pinochet say a resurgent revolutionary left is provoking the unrest.Some opponents of the seven-year-old regime suggest that the government itself may be behind incidents, allegedly perpetrated to discredit the left in the eyes of the public.

The series of encounters actually began in late April, with three bank robberies in a two-block sector of central Santiago. The police blamed the outlawed Revolutionary Leftist Movement, which has long been considered virtually defunct within Chile because of past repression.

Leftists, in turn, said the daring robberies could only have been carried out by a rightist group with connections inside the government. As the traditional May 1 rallying point for labor dissent approached, terrorist bombings proliferated. Police rounded up 500 persons two days prior to the holiday and, citing the danger of violent incidents, canceled permits for union rallies -- except a pro-junta gathering addressed by Pinochet.

Chile "will never return to the past," Pinochet told some 3,000 pro-government labor leaders invited to the junta headquarters. Pinochet has equated "the past" with political upheaval and labor violence.

More than 33 persons were arrested when the national police broke up a peaceful meeting of the United Workers' Front. This labor federation is tied through generally conservative labor groups to the AFL-CIO but is not recognized by the Pinochet government.

The junta even prevailed on Cardinal Raul Silva Henriquez, an ardent critic of military rule, to cancel his annual May Day mass. He said the "government and other sources" warned that violence would result if he carried out the 19-year tradition of saying a special mass that day.

Anti-junta labor unions had sought to demonstrate against the application of a decree last year that ostensibly revived the right to strike and bargain collectively but that effectively has maintained the government's absolute control of the workplace.

The decree was designed to head off an international effort to mount a boycott against Chilean exports. Even with pro-junta labor bosses as Leon Villarin of the truckers, who helped bring down the Marxist government of Salvador Allende in 1973, have criticized the labor plan.

Villarin's cohort, Juan Jara of the taxi federation, called the junta's economic planners a bunch of "pretty boys" who "hide behind bayonets" to carry out their policies.

Jara was thrown in jail for insulting the armed forces, making him a new hero of junta opponents.

In incidents since May Day:

Thirty-seven of those arrested at the outset of the month were banished to remote sites of internal exile akin to those used by the Soviet Union. Under an enabling decree issued in February, 51 persons, mostly young men, have been sent off in this manner.

The government announced discovery of a clandestine printing operation here, arrested 12 persons and tried to catch a Dutch priest who was accused of helping distribute the propaganda in rural areas. Police said the priest had since fled the country.

The director of the major opposition news magazine, Hoy, denounced a recent government decision to forbid printing of a companion magazine. "Once more the facts prove that in Chile there is no freedom of the press" said editor Emilio Filippi, who survived past closings and other intimidation of magazines he directed.