SAN SALVADOR, NOV. 26 -- Anonymous groups of the extreme right today issued veiled threats against the lives of returning leftist politicians and accused the armed forces of sitting by while the country is turned over to international communism.

"Do not lament when people, acting out of desperation, take justice into their own hands, and we find ourselves in the middle of a civil war for which you and {President Jose Napoleon} Duarte's Christian Democrats will be to blame," said a paid, unsigned statement addressed to the armed forces and published in the rightist newspaper Diario de Hoy.

It was the strongest public indication yet that the far right, which has been linked to political violence in the past, was not prepared to tolerate open leftist political activity in El Salvador.

{Later, a Chrisitian Democratic mayor was the target of an assassination attempt by the right-wing National Anticommunist Command, United Press International reported. Felipe Alvarenga, mayor of Ciudad Delgado and son of Aristides Alvarenga, vice president of the Legislative Assembly, escaped unhurt when he accelerated his car as three gunmen fired on it. Leaflets left at the scene said the command had attacked Alvarenga, "because he was of the Christian Democratic Party."}

The published threat came the same morning that leftist leaders Ruben Zamora and Guillermo Ungo said they had received anonymous telephone death threats while taping an interview at a local television station.

Ungo said that the two had received several telephone calls of threats to kill them, and several suspicious-looking men with "long suitcases" were spotted loitering in front of the station.

"We do not know who is behind it, but we believe they are trying to terrorize us," Ungo said. "Those threats along with the paid advertisements are part of a campaign to promote violence against us."

Ungo and Zamora, leaders of the Democratic Revolutionary Front (FDR), returned to El Salvador recently to test the political waters after seven years of exile, establishing the first open leftist political presence in the country since 1980.

The Democratic Revolutionary Front is a coalition of small social Christian and social democratic parties, and is allied with the Marxist-led guerrilla coalition, the Farabundo Marti National Liberation Front (FMLN).

Their return has sparked a flurry of leftist political activity and caused growing concern for their safety. Both men move around the city accompanied by foreign supporters, and Zamora wears a bullet-proof vest under his shirt.

Rightist groups, saying the leftist leaders are responsible for the actions of the guerrillas, demanded they not be allowed to return to the country, or if they returned, that they be arrested.

One page of the two-page statement had pictures of wounded civilians and soldiers under the headline, "These are some of the many victims of the assassins and executioners of our people, commanded by Ungo and Zamora."

"The only thing the commander and chief {Duarte} has not asked us to do is surrender, but the way things are going it will not be long until he does," said the advertisement.

"This will satisfy the assassinating jackals who now return as heroes with halos of saints, dressed as liberators of the people," the statement said. "But we, without losing hope or faith, pray to heaven the armed forces will react now because there is still time to save the country."

The far right in the past has been allied with the Army, but in recent years those groups have become disenchanted with the military.

"We are not asking for a coup d'etat, although if we look at the levels of incompetence, corruption and violations of the constitution, it would be justified," the statement said.