With increasingly dogmatic rhetoric, the Kremlin is showing deep concern about whether the Polish Communist Party can fully master the volatile free trade union movement born of last month's strikes.

The darkened Soviet view, detectable in a series of authoritative commentaries in recent days in the party paper Pravda and elsewhere, coincides with reports of new party turmoil in Warsaw over how to meet the union's demands, and persistent rumors here of an impending meeting between President Leonid Brezhnev and Stanislaw Kania, the new Polish leader.

Pravda, in an article last week clearly meant for Polish as well as Soviet readers, warned that Vladimir Lenin himself believed that trade unions in a socialist country can only be allowed to exist under party control.

And yesterday, in the latest in a series of articles thought to be cleared at the highest levels here, Pravda asserted that events in Poland have reached a "watershed."

"On one side of it are the patriots of socialist Poland," Pravda asserted, "and on the other the enemies -- both overt and covert. Normalization does not suit those who, by spreading rumors, ideas or 'projects' hostile to people's Poland, would wish to push Poland, and not only Poland, from the socialist path of development it follows."

This stark portrait is viewed by some Western analysts here as newly worrisome evidence of Moscow's opposition to the existence of the kind of independent trade unions envisioned by Poland's strike leaders. The Pravda commentary, written under the pseudonym A. Petrov, comes as the Polish labor leaders are threatening strikes next Friday if the government does not speed its compliance with the concessions it made last month.

Nothing is more authoritative in moments of doctrinal stress than a citation from Lenin, the founder of the Soviet state. Thus, Pravda's recollection that "Lenin more than once emphasized that trade unions can only fulfill their tasks in close cooperation and under the direct leadership of the party of the working class," has unmistakable, if seemingly ritualistic, significance in the public exchanges now going on between Moscow and Warsaw.

The Pravda writer, Prof. G. Alexeyev, added that the unity of party and people can only be guaranteed by "consistent observance of Leninist principles and norms." Observers here see this as a blunt warning to the Poles that there have been damaging deviations from those "norms."

Elsewhere in the East Bloc, the Czechoslovak Communist Party paper Rude Pravo, frequently a stalking horse for hard-line Moscow views, denounced a number of Polish dissidents as Mafia-style criminal "god-fathers" to the new trade unions. Reuter news agency reported Prague as warning that Jacek Kuron and other prominent Polish activists 'in the interests of their antisocialist aims, would not hesitate to plunge Poland and Europe into a new conflict."

While Pravda here noted that the Polish party had guided Poland's postwar recovery, observers see as significant that Petrov virtually ignored the Warsaw leadership's role in dealing with the present crisis. Instead the commentary declared, "There still are appeals heard inciting different categories of the Polish population to present unjustified economic demands designed to exacerbate the complexities facing the Polish economy."

Petrov warned that it is an open queston "as to who supports the processes of improvement and stabilization of the situation and who gleefully contemplates and is trying to be instrumental in exacerbating the difficulties in the way of the party and the entire Polish working class."

The article concluded with scarcely vieled references to the overwhelming Soviet interest in seeing the crisis resolved to the Kremlin's liking. "The Polish working people and the working class know full well that the genuine sovereignty and independence are guaranteed by fraternal unity with the other socialist countries, by the development of all-round and mutually advantageous cooperation."