Detailed allegations of increasingly brutal suppression of human rights activists in Czechoslovakia were published in London today amid reports that authorities in Prague are preparing a large show trial of dissidents.

The allegations, contained in an Amnesty International report, describe the attempt last year by two men to push a Charter 77 signatory in front of an approaching underground train, the beating up of another dissident in Ceske Budejovice in western Czechoslovakia and abuses such as limited detention, house searchers, surveillance, bugging, discrimination at work and loss of pension benefits.

The report by Amnesty International, a nongovernmental human rights watchdog group, expresses particular concern about the arrest and imprisonment of Czechoslovak nationals under the country's 1973 penal code. In Czechoslovakia, the report says, parts of the law "make it possible to construe the nonviolent exercise of international recognized human rights as criminal."

The Czechoslovak government maintains that international human rights treaties, like the Helsinki final act, are contracts among states and that individual citizens do not derive any rights directly from them. As a result, signers of Charter 77, a manifesto intended to remind the authorities of their obligations in the field of human rights, and members of the 1978 Committee for the Defense of the Unjustly Persecuted have found themselves the subject of special attention from the state security police.

Because of increased detentions, it is believed here that a large-scale show trial is on the way -- possibly within the next two weeks -- as part of a final attempt by the authorities to break the back of the human rights movement