Six Czechoslovak human rights activists are scheduled to go on trial in Prague today as Czechoslovak Comunists authorities add a new twist to their continued heavy-handed repression.

The six are accused of subversion in a long indictment implying that any protest by Czechoslovak citizens that is publicized in the West makes those involved guilty of subversive associations, even if they had no personal contact with "hostile forces" abroad.

Western analysts said the new argument contained in the indictment, which was smuggled out of the country, appears designed to stifle criticism of President Gustav Husak's government both inside Czechoslovakia and abroad.

Today's proceedings will be the first of three trials planned for eleven dissidents imprisoned in May.

In an apparently unrelated event, sources here said also that a dozen Roman Catholic activists, including several priests, were arrested by Czechoslovak authorities last month in a new antireligious drive.

The arrests of the Catholics are believed to reflect Prague's concern about the revival of religious activism following Pope John Paul II's visit to neighboring Poland last summer.

The six to be tried today include Vaclv Havel, an internationally known playwright, and two former spokesman of the Charter 77 movement. One of them, Jiri Dienstbier, was the Washington correspondent for CTK, the official Czechoslovak news agency, in 1969.

The six are charged with subversion "on an extended scale" conducted in collaboration with foreign agents and "inflammatory centers." If convictde, they face prison terms of up to 10 years.

The defendants, all members of an unofficial Committee for the Defense of Unjustly Persecuted Persons, are accused in the charges of "haughtily posing as some sort of supreme body in the state, entitled to give advice and decide who can and cannot be persecuted in Czechoslovakia."

Attempting to criticize Czechoslovak court decisions, the indictment argues, is an act of subversion since it undermines state authority and Czechoslovakia's interests abroad. It singled out the CIA and Amnesty International as "hostile forces" some of the defendants were allegedly in touch with, referring to the London-based human rights organization as a body that "systematically spreads slanders about Czechoslovakia throughout the world."

Charter 77 was a document signed by hundreds of Czecholsovaks. It drew attention to the Czechoslovak government's violations of human rights provisions in the 1975 Helsinki accords on security and cooperation in Europe. The document, published at the end of 1977, promoted a campaign of harassment against the signatories.

The Committee for the Defense of Unjustly Persecuted Persons is a subgroup of Charter 77 established to expose cases of alleged injustice and abuse of power by authorities. Its members argue that their declarations, mainly in the form of open letters to the Prague authorities, are entirely legal since the country's constitution provides for the right of petition and complaint.

The indictment insists that the "socalled open letters" were sent to "foreign inflammatory centers" and that they damaged Czechoslovak national interests abroad.