A United Nations report on world communications problems strongly favors press freedoms and urges that governments act to limit the power of large international news organizations and that journalists everywhere by guaranteed access to political dissidents.

The report released Friday, after a two-year study, will be debated at a general conference of the U.n. Educational, Scientific and Cultural Organization in Belgrade next fall, where it is expected to generate controversy about the rights and role of the news media.

The International Commission for the Study of Communications Problems that issued the report is headed by former Irish foreign minister Sean MacBride and is composed of journalists and government officials from 16 nations.

The recommendation on "transnational" news organizations -- the biggest are the U.S.-based Associated Press and United Press International, the British agency Reuter and Agence France-Presse -- was included over Western objections. The report does not specify what governments should do to limit the powers of these agencies.

For the Soviet Union, which believes the media should serve the interests of the state, the most troubling recommendation may be the one calling for journalists to have access to the entire spectrum of opinion within a country, including dissidents.