A leading Argentine human rights activist charged here yesterday that the capture of two Peronist political leaders in Buenos Aires Wednesday constituted revival of the military government's officially repudiated "disappearances" policy.

Witnesses said 16 heavily armed men broke into a Peronist party office, identified themselves as federal police, and took away Julio Barbaro and Juan C. Gallegos. Police later denied any arrests, and nothing has been heard since of the two men.

Rights activist Emilio F. Mignone, visiting in Washington, charged the action "makes clear that the practice of disappearances and illegal repression are still the norm in the Argentine military regime, despite the denials of its functionaries." He and other rights activists contended that the massive action, in daylight downtown, could only occur with official complicity.

An Argentine Embassy spokesman said the president, Gen. Roberto Viola, had ordered a full investigation of the disappearances.

Mignone noted that they occurred as Foreign Minister Oscar Camilion was in the United States making assurances that arbitrary repressions by security forces were a thing of the past. In the three years following the military coup of 1976, from 5,000 to 15,000 Argentines disappeared, most now assumed to have died at the hands of security forces.

In contrast to that period, Buenos Aires newspapers have given broad coverage to the latest case.