MAPUTO, MOZAMBIQUE, DEC. 17 -- President Joaquim Chissano proposed a general amnesty today for anticommunist guerrillas who have attacked this struggling country for its entire 12-year history.

Addressing the opening session of the legislature, Chissano said he will appeal for international help to put the amnesty into effect. He asked the assembly to codify a de facto 1984 amnesty, presumably because a legislated offer would be more likely to attract overseas aid.

The amnesty would extend "without exception to all those who want to leave their activities of terrorism and crime," Chissano said. He said he wanted to build "reception centers" where rebels could lay down their arms and learn rural skills.

Mozambique's first president, the late Samora Machel, declared an amnesty in 1984 after signing a nonaggression pact with South Africa, which until then had supported the rebel Mozambique National Resistance, or Renamo, openly. Since then, despite a trickle of defections, Renamo has grown larger and more destructive with alleged covert South African support.

Under Machel's amnesty, the military tribunals that once sentenced captured guerrillas, frequently to death, were disbanded and the few rebels who have been seized or have surrendered since have been returned to civilian life.

Those cases are rare, however, because the rebels apparently know the destitute Marxist government here has few resources to help them start again.

The amnesty's success "will depend on what the rehabilitation centers are like," said Rob Davis, who works with the Center for African Studies here. "If the offer is reasonable, it could attract a lot of people."

That in turn could depend on whether donor governments answer Chissano's appeal. "If there is a big response it could create other social problems," said Marta Mauras, a U.N. representative. "The government already has a lot of people to take care of."