The most prominent leaders of Eurocommunism, Italy's Enrico Berlinguer and Spain's Santiago Carrillo, reviewed tactics and strategies in a series of closed-door talks here today with the aim of revitalizing their controversial theory of democratic socialism.

Informed party sources said that both leaders would reaffirm their commitment to parliamentary democracy and would seek to broaden their policies to embrace mainstream socialist parties with the intention of formulating a united left-wing strategy on a European scale.

However, the sources said that calls for unity fell short of seeking joint platforms or even specific common programs and that there was no question of reactivating the popular fronts of the 1930s.

The reappraisal of the original Eurocommunist position, which marked out the differences from the Soviet model, comes as both Italian and Spanish Communists have seen the results of their tactical shift fall short of their expectations.

Berlinguer, who arrived from Portugal last night for a two-day working visit in Madrid, has seen his hopes for an agreement with the ruling Christian Democratic Party in Italy within the framework of the so-called "historic compromise" unfulfilled and largely discredited.

In the "historic compromise," the Italian Communist Party, which normally gets about 34 percent of the popular vote in elections, said it would work within the system to gain power, even if that meant joining a coalition government with the Christian Democrats. So far no such coalition has been formed, although the Italian Communists have refrained from scuttling weak Christian Democrat-led governments in tacit agreements under which the Communists have a voice in policy-making.

Carrillo's calls for a government of national unity in Spain have been systematically rejected, and he has failed to gain more than 10 percent of the vote in elections -- less than half the Socialist share of the electorate.

Both parties appear to have progressed little since Eurocommunism was first clearly defined in 1975 when Italians and Spaniards hammered out the so-called Livorno Document and undertook to build socialism through democratic, parliamentary means. But the two organizations still stand by this commitment and their outspoken break from the tutelage of the Soviet Union.

Unlike a meeting between Berlinguer and Carrillo 2 1/2 years ago, there is little fanfare surrounding the current talks. When they met in Madrid in February 1977 with French Communist leader Georges Marchais, the conference was highly publicized, giving an impression that Eruocommunism could take southern Europe by storm.

Manuel Azcarate, a veteran Spanish Communist and the party's Central Committee member in charge of external relations, said this weekend that the whole context of the present discussions was "very different."

"Since Lovorno and the 1977 Madrid meeting, we have begun to have credibility," Azcarate said. "Our problem now is to come with the answers, on a European scale, to the crisis that the continent is undergoing. Unless we can face the crisis with a positive response it will appear that Eurocommunism is frozen."

Party sources said that Berlinguer and Carrillo were seeking to make Eurocommunism a broad left-wing alternative to what they view as a deep economic crisis facing all of Europe. Their discussions have focused on ways to formulate common strategies with socialist parties that have hitherto stood aloof from the Communists, the sources said.

Faced with a double rebuff from the ruling Christian Democrats who refuse to have Communists in the Italian government and reject the "historic compromise," Berlinguer has reached an agreement with the Socialists by which both parties agree to oppose jointly any official discrimination against members of either one.

Carrillo, for his part, recently said in a major policy speech at a Madrid Communist rally, "The people must see Socialists and Communists overcoming their narrow party interests and working together for the future of the country, for the consolidation of democracy and for the creation of a new society."

Azcarate explained that in the same way that Communists, particularly in Italy and Spain, had broken away from Moscow and rethought their basic principles, European Socialists should reconsider their adherence to the moderate policies of social democracy in view of Europe's economic difficulties.

"There is certainly new socialist thinking in Austria, Britain and in Sweden," Azcarate said. "The forum for a left-wing alternative should be the European Parliament, to which Spain does not yet belong but which Spanish Communists are already monitoring closely."

Berlinguer is also scheduled to meet Spanish Socialist leaders during his stay here.