BOGOTA, Columbia--Government negotiators yesterday offered a deal believed to include safe conduct out of the country to terrorists holding U.S. Ambassador Diego Asencio and about two dozen other diplomats.

The proposal included flying the guerrillas to either Algeria, Libya or another Third World country not immediately identified, according to sources close to the government.

There was no confirmation of the safe conduct proposal from either the government or the guerrillas.

Diplomatic sources said yesterday three Latin American countries--Mexico, Costa Rica and Panama--have also offered the guerrillas political asylum.

The proposal was offered during the second round of face-to-face talks in a windowless van parked outside the Dominican Republic Embassy, scene of the week-old takeover.

The terrorists, members of the M-19 guerrilla movement, demand $50 million in cash, the release of political prisoners, worldwide publication of a guerrilla manifesto and a safe conduct pledge.

They have threatened to kill their hostages--20 foreign diplomats, two Colombian foreign ministry protocol officers and an undetermined number of others--and blow up the embassy if their demands are not met. They say they are willing to wait as long as two months for a settlement.

Government officials have said they expect no resolution to the situation before Sunday's municipal elections.

The cream colored panel truck, the same one used in last Sunday's first round of direct talks, yesterday arrived shortly before 9 a.m. and was parked with its back door facing the embassy. The rear doors were removed to allow guerrillas inside the embassy to observe the talks.