Salvadoran Provisional President Alvaro Magana said yesterday that his country's armed forces will observe a truce in the civil war during Pope John Paul II's visit Sunday.

In response to a Feb. 25 plea from 14 U.S. senators, Magana said in a message released by the Salvadoran Embassy: "I am happy to state that my government, so peace may prevail, will not institute on that day any activities which might result in armed conflict or violent situations."

The Farabundo Marti National Liberation Front guerrillas said Monday in Mexico City that they would observe a one-day cease-fire.

Meanwhile, a military spokesman in San Salvador said yesterday that a guerrilla suspect had told security forces of a plot to kill the pope.

Defense Ministry spokesman Col. Alfonso Eusebio Cotto told reporters that security agencies had "indications" that 18 sharpshooters entered the country recently with the mission of assassinating the pontiff during his 10-hour visit Sunday.

"I am not saying it is true," Cotto said. "I am saying there is an indication." He said security agencies got the information from a guerrilla suspect who was hit by a car trying to flee detectives and died soon after. He said that before the suspect died, he described the plot and handed over a breakfast cereal box containing 18 passports.