THE RUSSIANS seem to have discovered a terrific new synthetic fuel. It's called books. There is an endless supply of them to be imported from America; thereupon they can be seized and consigned to the incinerator. True, it's not yet certain that this is what the Russians are really up to at the so-called book fair they are sponsoring in Moscow or that the confiscated books are actually being burned. But it is as good a justification for what is going on as any you are likely to hear and probably better-- that is, a lot more respectable-- than the truth.

"Moscow Book Fair Marred by Censorship, Visa Disputes," a headline in this paper accurately reported on Sunday. "Marred" is such a wonderfully right and resonant word here, expressing, as it so often does, in the most positively decorous way, a situation that is plain ruin. One thinks of the chaplain in that Evelyn Waugh novel, staring bemusedly into the middle distance and murmuring his vague reproach to the mothers at the school parents-day event who had fallen to hideous fighting and name-calling among themselves -- "I think unpleasantness so mars the afternoon" likewise censorship, not to mention confiscation, can really mar your basic, all-purpose international book fair.

First there was the fracas over the Soviet authorities' refusal to issue a visa to the president of Random House books, Robert Bernstein, whose exertions on behalf of human rights around the world, including in the Soviet Union, have evidently been too much for them. Then there was the voracious appetite of the Kremlin book-banners whose triumphs were reported over the weekend in the manner of a holiday death toll-- the number of bannings kept being expected to grow, and the expectations were not disappointed. By Monday UPI was talking of about 40 confiscated works. By Tuesday AP reported that 44 books had been confiscated.

Boris Stukalin, the chairman of the Soviet state publishing committee, undertook to explain it all to a curious public. He said of the banned books: "They cannot be permitted for exhibition because they do not serve the purpose of detente, they do not serve the spiritual exchange of mutual understanding between peoples, but encourage hostility." Mr. Stukalin elaborated by noting that freedom of expression was not involved here, but (what else?) "freedom of fascists propaganda."

Appropriately enough, the American embassy in Moscow has responded by calling off the gala reception planned to honor this great literary event. One's first instinct is to say the Americans should simply pick up their books and go home. But because there is a certain residual value to these events, despite the pervasive elements of sham, Americans publishers and government officials should probably take another tack. This time, having decided to participate, they have done the right thing in making a ruckus and exposing the authorities for what they are. Next time, if there is one, they should make it plain in advance what the terms and conditions of participation are-- and these should include, at a minimum, an outright ban on the banning of books by the Soviet authorities.