Perquin, the first significant government outpost ever taken by Salvadoran guerrilas, has been recaptured by the Army, according to journalists who visited it yesteday.

The town of about 3,500 people in the northeast near the Honduran border is now reported to be almost deserted. It was held by Marxist-led insurgents for more than a week and represented a major prize for the guerrillas, who are believed seeking enough territory to establish some form of rebel government.

Army spokesmen have said over the last several days that they had retaken the town or were about to. But it was not until yesterday that some local journalists were allowed in to verify it.

Some of those journalists said they were told by the few remaining civilians that as many as 500 guerrillas occupied the town at one time. The Army, which had tried unsuccessfully to move large numbers of troops up the main access road from the regional capital, San Francisco Gotera, finally retook Perquin, military spokesmen said, with about 100 soldiers.

The guerrillas' clandestine Radio Venceremos was still claiming leftist control of the village as late as Wednesday night, but since then has carried no such reports.

Perquin is at the center of a mountainous region that traditionally has been one of the guerrillas' greatest strongholds. But while the left has been able to hold its own in the rough countryside, and cause economic damage throughout the nation by sabotaging public utilities, it previously had little success in asaults on towns.

The Perquin garrison, manned by at least 21 members of the Salvadoran National Guard, was taken by the insurgents Aug. 10 According to reports in local newspapers today, at least three guardsmen were killed at the time, three taken prisoner and the rest were found wounded.

Most residents evacuated the town as soon as it became a point of contention and civilian casualties appear to have been kept at a minimum.