OBVIOUSLY, the Kremlin does not share its secrets with capitalist western record companies. In fact, given the disregard that Chairman Brezhnev seems to feel toward the conductor and principal singer in this superb recording, he might have had second thoughts about the timing of their banishment from their homeland had someone suggested to him that a secondary effect of the publicity might have been to drive up sales of this recording. No matter. Rostropovish's performance of Tchaikovsky's The Queen of Spades (Deutsche Grammophon 2711 019, four records) or Pique Dame, as it is labeled on this set, would have been an important musical event anyway - regardless of its political spinoff.

It is, quite simply, the finest phonographic achievement yet of Rostropovich the conductor. His two previous complete opera recordings and his symphonic recordings have certainly had their moments, but one's reactions were always qualified. Here one feels no such qualifications.

This moody drama loosely based on a Pushkin short story about the consequences of the homicidal, and ultimately suicidal, gambling obsession of Hermann, a low-ranking army officer, is Tchaikovsky at his most gripping. For the performers, it is also Tchaikovsky at his most challenging. At least six singers of top caliber are needed. The rich, complex orchestral part cannot be slighted. The choruses are many and beautiful. To all this Rostropovish and his cast have risen on a level previously unmatched on discs.

But if Rostropovish is the leading star of this performance because of the intensity with which he interprets Tchaikovsky's grim fatalism, his wife, Galina Vishnevskaya, is a close second as Lisa. Just listen to the subtlety of inflection in her lament for her lost love, just before she is about drown herself in the Neva. This is a major singer at her very best.

The noted American mezzo, Regina Resnik, sings the role of Lisa's grandmother, the countess, from whom Hermann is out obsessively to pry the crucial secret of the tree winning cards. She is the dramatic equal of Vishnevskaya. Her voice is not what if once was, but this may actually be a plus in interpreting the role of a very old lady.

The role Hermann goes to Peter Gougaloff, a 48-year old Bulgarian tenor who is a resident at Berlin's Deutsche Oper.He may not have the ringing high notes that the Bolshoi's Vladimir Atlantov brought to the role during that company's visits here in 1975, but he is a vocal actor of the first rank. The rich baritone of Bernd Weikl as Prince Yeletsky sounds every bit the aristocrat Tchaikovsky and Pushkin intended.

Another marvelous moment comes when Dan lordachescu tells the story of the countess, and how she came to have the secret of the cards, in Count Tomsky's ballad. And yet another index of the riches that Rostropovich can command is that the celebrated coloratura Lucia Popp sings the brief role of Chloe in the intermezzo staged in the party scene.

The Orchestre National de France plays far above its customary level on this set. The same is true of the two choruses, the Tchaikovsky Choir and the Matrise de Radio France.

The National Symphony's conductor is said to plan an extended series of complete recordings of Russian operas. With this Queen of Spades as a standard they could become musical landmarks.

One final word. If Rostropovich can do this on records from Paris, why can't he do it for the Washington Opera, with the National Symphony in the pit? The Met's splendid Queen of Spades sets could be borrowed and the same cast could be reassembled. To have him here for several months a year without hearing any opera is a waste.