President Alvaro Magana, in his first response to a formal proposal for peace talks by El Salvador's left-wing insurgents, today ruled out negotiations as long as the guerrillas carried arms.

But the president's carefully phrased statement, read over the national radio, appeared to leave open the possibility of a dialogue after a cease-fire.

The five guerrilla groups under the umbrella of the Farbundo Marti National Liberation Front and its political wing, the Democratic Revolutionary Front, last Wednesday issued a five-point proposal for a direct dialogue without preconditions to bring peace to El Salvador.

In his response today, Magana said there could be no participation of armed groups in the process of developing democracy here. The president repeated earlier calls on the insurgents to lay down their weapons and take part in the "democratization" of the country.

The statement spotlighted the wide gulf in the positions of the warring sides and underlined the problems of ending a conflict in which at least 34,000 people are estimated to have died.

Western diplomats here said the combat groups were unlikely to surrender their weapons in the absence of a clear-cut amnesty program and gyarantees of personal safety for guerrillas who opted for ballots rather than bullets.