The Soviet Union made another strong attack on the Solidarity independent trade union organization tonight in a move clearly linked to a key meeting of the Polish Communist leadership that began today in Warsaw amid more labor strife.

The official Tass press agency said that "Solidarity has stepped up its subversive political agitation among the population" in coordination with KOR, the dissident human rights organization and other "antisocialist groups."

Continuing the harsh denunciations of the past two weeks, Tass said: "The Solidarity leadership is trying to mount a campaign of unbridled slander against the Polish United Workers Party [the official name of Poland's Communist Party] and is organizing attacks on the socialist system in Poland."

Moscow's tough words coincide with a meeting of the Polish Communist Party Central Committee at which hard-liners opened with calls to limit Solidarity's grounds for calling strikes and included denunciations of its ties with KOR, the major Polish dissident group.

Tass accused KOR leader Jacek Kuron and others of conspiring to travel throughout the country "to many provinces and major enterprises to agitate the population against the party decisions." The blunt language of the official press agency reflects the anger of the Kremlin leadership that Solidarity and the independent trade union movement continues to gain victories in its showdowns with the Polish party and government.

Tonight, tass accused one of Solidarity's leaders, whom it identified only as "Michnik," an apparent reference to dissident Adam Michnik, as having declared that "Solidarity in fact is a political party and that, considering the current situation, this trade union organization should take on itself political functions." Tass also accused Kuron of calling for "changing the political system.