Insider tells what happened to Brezhnev, where's Kirilenko, why Reagan rebuffed

A senior Soviet official has confirmed that President Leonid Brezhnev was hospitalized after an ''accident'' at a factory he visited last month, but denied Western reports the Soviet leader had suffered a stroke.

The official suggested that the President, who appeared in public April 22 for the first time in four weeks, was recovering well. Mr. Brezhnev is tentatively expected to keynote a congress of the Communist Party youth organization in late May, the source said.

The unprecedentedly detailed official account of Mr. Brezhnev's health for a Western news outlet came on the heels of the president's first public appearance in four weeks, and seemed aimed partly at countering Western reports suggesting Mr. Brezhnev's condition had been critical.

The Soviet official, in an hour-long conversation with the Monitor April 23, also went some way toward confirming reports that a Brezhnev Politburo colleague , Andrei Kirilenko, was ill.

The Soviet source sits on the Communist Party Central Committee and is in regular contact with members of the Politburo and Central Committee Secretariat.

''President Brezhnev was in the hospital,'' the official said. ''He got out about a week or so back.''

According to the official, Mr. Brezhnev was hospitalized on his return to Moscow in late April from a visit to the Asian republic of Uzbekistan. ''There was an accident in a factory he was visiting. He fell down and hurt himself.

''He hurt his arm. He was given preventive injections and continued his (Uzbekistan) program,'' the official said.

He said that in light of Mr. Brezhnev's age, the president had ''naturally'' undergone various tests in the hospital, but had also done some work during his stay.

The official gave no further details of the factory accident, but earlier reports from unofficial Soviet sources said a platform had collapsed with a crash during Mr. Brezhnev's visit and that an alarmed aide or bodyguard had bundled the president to the ground.

On other issues, the official:

* Charged that President Reagan's April 5 suggestion to reporters that it ''would be very well'' if Mr. Brezhnev met him informally in New York this June was ''one in a series of propaganda tricks.'' The Soviet official implied this seemed particularly true considering that Mr. Reagan's comments had coincided with Western reports that Mr. Brezhnev was hospitalized. The official emphasized that a Soviet counter-suggestion April 18 for a summit in Western Europe this fall ''should be seen as reflecting our genuine support for talks. It is a serious proposal.''

* Said that Politburo member Andrei Kirilenko had been out of Moscow for some time and was ''resting in the south of the country.'' The official did not explicitly confirm reports that the 75-year-old Mr. Kirilenko, once tagged by Western diplomats as Mr. Brezhnev's likely successor, was ill. But the source did say that ''obviously'' a man of Kirilenko's age ''does not take this sort of rest if he is feeling okay.''

* Denied Western news reports that a meeting of the full Communist Party Central Committee set for early April had been postponed during Mr. Brezhnev's hospitalization. No firm date for the committee session had been set at that time, the official said. But he did assert that a meeting is planned for sometime in the next six weeks or so.

The Soviet source indicated it was possible the meeting would consider top personnel changes in light of the passing in January of Mikhail Suslov, the senior party ideological authority and a member of the Politburo.

The official also confirmed earlier private remarks from other Central Committee members that some of Mr. Suslov's formal briefs had thus far fallen to Konstantin Chernenko. Mr. Chernenko is a Politburo member and longtime Brezhnev aide who is seen by foreign political analysts here as one possible successor to President Brezhnev.