Alexei Nikitin, the Soviet mining engineer incarcerated in a mental hospital after talking with Western correspondents, has been allowed to meet with his relatives, his first contact with outsiders, since he was seized by police Dec. 12, reliable sources reported today.

The resources said Nikitin, 41, who was sent to a special psychiatric hospital run by the Inter Ministry in Dnieprepetrovsk, Ukraine, received multiple injections of unknown drugs from mid-January to mid-March, bringing him severe pain and disorientation.

Nikitin was held in quarantine, a form of isolation, the sources said, until late March, when he was allowed to meet with relatives.

Nikitin was arrested after guiding two Western reporters around the Ukrainian mining city of Donetsk for several days. He has been in confrontation with Soviet, authorities for more than a decade over mine safety and workers rights.

The sources said that Nikitin was no longer in pain but reportedly had lost much weight because of the treatments. They said it is not knwon whether the treatments were resumed after the relative left Dnieprpetrovsk. The Soviet Ministry of Health and the Interior Ministery have denied any knowledge of Nikitin or his whereabouts.

Meanwhile, sources reported that the authorities have been interrogations of friends and relatives of Anatoly Koryagin, the Kharkov psychiatrist who was arrested after publicly declaring Nikitin to be mentally sound. Koryagin, 42, a consultant to an unofficial dissident group investigating Soviet political abuse of psychiatry, had been held in isolation in Kharkov city jail since his arrest several months ago, sources said. The state has accused him of anti-soviet agitation for his activities.