Five days into a broad offensive, the leader of El Salvador's political and guerrilla opposition movements said today that they are willing to start direct negotiations with the United States to seek a political solution to avoid further bloodshed in that Central American country.

Saying he was speaking for both the left and center-left political opposition as well as the five Marxist guerrilla organizations who make up the Salvadoran opposition, Guillermo Ungo said, "We are seriously interested in talks with the U.S. to find a political settlement. We are saying this to the Carter and the Reagan administrations. If we wait for a military victory, the exterminaiton of the people will be so much greater. Hundreds of women, children and old people are being killed."

Ungo, a Social Democrat leader in El Salvador, said that the talks should be held directly with the United States, rather than the current Savadoran government, since "the United States has been demonstrated to be the power behind the Salvadoran throne. It has contribute to the radicalization and the polarization of the process. It therefore has a quota of responsibility.

"We want to talk to the owner of the circus, not to the acrobats," he said.

[at the State Department, Deputy Assistant Security James Cheek responded, "The evidence that emerged from the offensive, captured documents raises some serious questions about the ownership of the front mr. ungo represents."]

Ungo replaced Enrique Alvarez as head of the opposition Democratic Revolutionary Front after Alvarez was killed along with five other opposition leaders in El Salvador last November. He and other representatives of the opposition umbrella group said front representatives met with U.S. Assistant Secretary of State for Latin American William Bowdler and his deputy for Central America, Cheek, late August.

Since then, they said, there had been only informal contacts with U.S. diplomats in the region, although "we showed our willingness to keep relations and communications [open] with the U.S."

Last December Ungo said, State Department officials first indicated that United ystates was willing to talk about restructuring the government in El Salvador. But in late December, he said, they told the front the opposition should negotiate directly with the Salvadoran government.

[A State Department official acknowledged talks, as distinct from negotiations, with opposition leaders including ungo as late as August but he denied any conflicting signals. The thurst was always to encourage negotiations within El Salvador, the official said.]

At a later press conference, sokesmen for both the guerrillas and the politicians denounced the renewal of U.S. military aid to El Salvador and charged that troops from both Honduras and Guatemala have entered the war on the side of the Salvadoran military.

The U.S. claim that it is offering the Salvadoran government "nonlethal" weapons, including helicopters, is false, they said, because helicopters were being used to kill the civilian population.

While they charged that three already had been several incursions by the Guatemalan Army in western El Salvador, where the two countries share a border, the spokesmen said Honduras has agreed to send about 3,000 troops to help seal its border starting Thursday.

The military government of Honduras previously has denid any involvement in the Salvadoran civil war. Spokesmen for Honduras and Guatemala could not be reached today for comment.

The Salvadoran opposition leaders are visiting Mexico to announce the formation of a seven-member "political-diplomatic" commission, which has "plenipotentiary power" over the myriad civilian and guerrilla umbrella organizations making up the leftist coalition.

The commission, its members said today, will start preparing a new Salvadoran government and will launch an international diplomatic effort to avoid outside military intervention.

The seven Salvadorans who appeared at a press conference here included Ungo, former education minister Salvador Samayoa, who represents the National Liberation Front and guerilla commander Ana Guadelupe Martinez of the Revolutionary People's Army, one of the five guerrilla groups.

Both Ungo and Samayoa held posts in the government formed after a U.S.-backed coup in October 1979. They resigned early last year following charges that government security forces were involved in repression against Salvadoran peasants. All three are expected to become members of an opposition government in exile.

This week, members of the group met with Mexican government officials including the official party leader Gustavo Carvajal, who has been critical of the Salvadoran government and given moral and political support to the opposition.

Commission members will now travel to Canda, Sweden, West Germany, Austria, Algeria, Yugoslavia and Libya to muster further support, they said.