Moscow — The man who has run the Soviet KGB since 1967 is reliably said to have left that post, capping a political shuffle that places him near the pinnacle of the Communist Party hierarchy and firmly in the running to succeed Leonid Brezhnev.
Yuri Andropov's departure from the KGB - to be announced ''soon,'' according to a senior Soviet source - follows an official statement May 24 that he had been named to the Communist Party Secretariat.
The KGB leadership had been seen by foreign analysts as a potential handicap to Mr. Andropov's prospects of becoming party leader after Mr. Brezhnev.
Senior officials say privately that the Secretariat posting makes Andropov, who is not a career KGB man, one of the two most important political figures behind Brezhnev. The other is Konstantin Chernenko, a longtime Brezhnev aide. Both sit with Brezhnev on the party's ruling Politburo.
In a sense, Andropov and Chernenko, strikingly different personalities, may already be vying for top day-to-day power in a nation nominally ruled by Brezhnev.
In a political system where Western onlookers must judge largely from the stiltedly printed word, little can be said with certainty of the political views of either Andropov or Chernenko. Both, in published words, have sounded different from issue to issue, time to time.
If either, indeed, does rule the Soviet Union, his policies would probably draw a lot more on the political environment he faces than on the words he, or his speechwriters, once crafted.
But officials who know both, and their publicly printed biographies, sketch these portraits:
* Chernenko has, indeed, risen alongside Leonid Brezhnev. But since joining the Secretariat in 1976 and the Politburo shortly afterward, he has become gradually much more than a mere Brezhnev aide. As head of the so-called ''general department'' of the Secretariat, he is responsible for channeling all policy papers and reports commissioned from outside.
''In foreign policy,'' says another senior Soviet source, ''Chernenko has been involved more or less since 1975. . . . He has absorbed some experience.'' He is described as not startlingly bright, garrulous, or articulate, but as an avid and capable study on policy issues who possesses a ''gift for surrounding himself with capable people.''
* Andropov has a long and varied party record, with particular experience in foreign affairs. He was ambassador to Hungary during the Soviet military intervention there in 1956, then became a Secretariat member dealing chiefly in relations with East-bloc Communist parties. He has never made an official trip to the West.
When he left an earlier Secretariat post to head the KGB, the move was in effect part of a bid to cement civilian party control of the secret police apparatus.
Personally, Andropov is portrayed as a contradictory figure. He can be very tough. But those who know him say he likes to read literary, as well as political, volumes. Once, according to Soviet sources, he even dabbled in writing poetry.
The nine-man party Secretariat that Andropov will join is charged with implementing policy lines drawn in the ruling Politburo. Of late, Chernenko has tended to chair the Secretariat.
Asked if Andropov might share that role, one senior official said privately that this was very likely. ''There are in Iffect two main figures on the Secretariat,'' he said, ''Andropov and Chernenko.''
Two other party leaders, besides Brezhnev, are full members of both the Politburo and the Secretariat. One of them - Andrei Kirilenko - is said to have been seriously ill of late. The other - ''youngster'' Mikhail Gorbachov - is moving beyond his specialization on agricultural issues but is seen as lacking the political clout of an Andropov or Chernenko