Leaders of El Salvador's leftist rebel coalition said yesterday that formal talks on a cease-fire with the Salvadoran government will come only after progress in lesser matters, but that the guerrillas might declare a unilateral Christmas truce.

Officials of both the armed guerrilla coalition known as the Farabundo Marti National Liberation Front (FMLN) and its political arm, the Democratic Revolutionary Front (FDR), also said they were united in willingness to consider taking part in March municipal elections, but that steps to "humanize the conflict" must come first.

Hector Acevedo, member of the FMLN's moderate National Resistance faction, told Washington Post editors and reporters that humanizing would mean formal recognition of the Geneva Convention rules calling for neutral and humane treatment of casualties and prisoners in El Salvador's five-year civil war.

FDR chief Guillermo Ungo said the coalition had proposed meeting for a second time with the Salvadoran government on Nov. 27 in the capital, San Salvador. The left had been expected to suggest holding the talks in northeastern Morazan province, where they hold territory, to facilitate participation by guerrilla commander Hector Villalobos. But Ungo said a meeting in the capital could be just as secure and would test the government's commitment to talks.

A cease-fire would only be discussed "not as a first step, but in the middle of the road when we've proven enough political will to make deals, not just to talk," Ungo said.

Ungo said the leftist coalition is considering a unilateral Christmas truce along the lines of the cease-fire that observed Pope John Paul II's visit to El Salvador in March 1983.

He reiterated the coalition's desire for an eventual share of power in the Salvadoran government, but said the group is "considering our participation" in the March elections.

Government officials, he said, "take for granted that we will not participate" because of the short time left for preparations.

At an earlier news conference sponsored by Foreign Policy magazine, Ungo said, "We are not going to be just watching the election. We will participate somehow."

He added, "We will tell the Salvadoran people what is our position and we will ask the Salvadoran people to support that position."