President Mikhail Gorbachev scored a major political victory in securing the resignations of nearly one-third of the Communist Party Central Committee, a move that will allow him to promote supporters of his reform policies.

Gorbachev described the mass resignation Tuesday as a "serious regrouping" made necessary by the new era of reform in the Soviet Union.He also linked the resignations to unprecedented multicandidate elections last month in which several powerful party bosses failed to gain seats in a newly created national legislature.

"Now, particulary after the election campaign, the situation has changed considerably, comrades," Gorbachev told Central Committee members. "Vast changes have taken place over this period, also in state (government) bodies, and this required personnel changes."

The biggest head to roll was that of Andrei Gromyko, 80, who was foreign minister for 28 years and was forced to step down as president last Oct. 1. The somber Gromyko once noted that Gorbachev had a "nice smile, but teeth of steel."

Politburo member Vadim Medvedev said 83 full members of the 301-member Central Committee and 27 alternate members or members of the auditing commission had resigned for "health and personal" reasons. He said 24 other alternate members were promoted to full membership.

Gorbachev, whose speech was quoted by the official Tass news agency, noted that 83 Central Comittee members at the start of the plenum Tuesday were already on pension, as well as 27 of 157 alternate members and 12 of people on the party's auditing commission.

"A total of 122 people serving on the party's central bodies are at present pensioners," he said. "(But) life today, its dynamics and scope, and the tasks facing the Central Committee, demand further and even much greater activity."

One Western diplomat said, "It is not clear whether their hands were forced and (whether) they were told in fact to quit."

Medvedev, who said there was no rule fixing the number of members of the Central Committee, described the overhaul as an "important milestone" for Gorbachev's reform program.

The resignations may have represented a consolidation of Gorbachev's power in the past nine months. He tried unsuccessfully last June to rid the Central Committee of one-fifth of its members at a special party conference.

A Western diplomat said the fact that some officials who won overwhelming victories in the election last month were not on the list of those promoted shows that Soviet democracy is still very much in its infancy. He said the same was true of the fact that some election losers did not resign.

Medvedev said Gorbachev read the request signed by those who asked to resign. The request said those resigning had "retired on pension either because of age or for health reasons."

The resignations included 11 former associates of Leonid Brezhnev, ridding the Central Commitee of the late Soviet leader's favorites and removing the last vestiges of a period now described in the official media as "the era of stagnation."

Others ousted included Geidar Aliev, 66, a former head of the Republic of Azerbaijan and former member of the ruling Politburo who was said to be a one-time rival of Gorbachev for the top job, and former First Deputy Defense Minister Marshal Nikolai Ogorkov.