The Spanish Communist Party (PCE) has just bought a two-page advertisement in a newspaper here denouncing Soviet-style communism and the crackdown in Poland.
That Spanish Communists should have to rely on paid publicity in the capitalist press to publicize their profound disgust with Soviet communism shows just how far the leadership has burnt its bridges with Eastern Europe. It also shows just how embarrassed the Spanish Communists, led by veteran Santiago Carrillo, have been by events in Poland.
The Spanish Communists have been every bit as critical of Moscow as their Italian comrades. But they have managed to escape the near-excommunication that befell the Italians. This is partially because they are not so influential on the Spanish political scene. They have about one-third the popular support (9 percent) that the Italian party has.
But more important, the party is not so monolithically anti-Soviet. It still contains a core of hard-liners, some of whom fought with the Red Army during World War II, who owe unswerving allegiance to Moscow.
The Kremlin has no interest in alienating these people, whom it has been supporting in what Mr. Carrillo's supporters regard as a dirty propaganda war. Only two weeks ago Carrillo accused Moscow in all but name of trying to destabilize the party.
Carrillo has long ceased to be sympathetic to Moscow's Leninist ideology. A ''Eurocommunist, he believes the Western Communist parties can influence the electorate in bourgeois Western democracies only by showing their independence from Moscow.
Unlike their Itlian colleagues, the Spanish Communists still have to fight for political respectability. The leadership is sufficiently astute to know that in the delicate political balance of Spain, with the military never having forgiven the party's legalization in 1977, they cannot tread too extreme a path. The right in Spain jokes, unkindly but correctly, that Mr. Carrillo is the biggest supporter of the monarchy in Spain.
These contradictions, combined with Moscow's pressure, have helped to cause serious tensions within the party. The tensions have been accentuated by the increasing authoritarianism of the man who has led the party for 21 years.
Moscow knows, as does Carrillo's own party, that people are beginning to line up against a change in leadership. Ironically, he has alienated those members most publicly identified with Eurocommunism, like Manuel Azcarate, expelled in December from the Central Committee, where he had been in charge of foreign affairs. Dissidents like Azcarate accuse Mr. Carrillo more in sorrow than anger, of being insensitive to the needs of the party and refusing to delegate authority.
The divisions have proved so serious that there has been an unprecedented number of defections, including persons in public office, notably in Madrid city hall. This has caused the rupture of a pact with the Socialists to run jointly some 20 of Spain's major city halls.
At a recent press conference, Mr. Carrillo was undeterred by hostile questions about the deteriorating state of the party. His tongue-in-cheek reply to an opinion poll giving the Communist Party only 5 to 6 percent of the vote was: ''Just before the last elections they showed us with only 2 percent of the vote and we got 9 percent, so this must be good news.''
Analysts say an important, disgruntled rump of Communist voters will switch to the Socialists at the next elections. But those who know Mr. Carrillo say he prefers to operate with a smaller party that is utterly loyal, and that could if necessary go underground, should the military come to power.