BALTIMORE becomes a world theater capital from Sunday through June 29 as it plays host to the Theater of Nations Festival, an important and eclectic mix of theatrical styles and voices, with a dozen nations participating at a variety of city venues.

Accessibility for American audiences was a prime consideration in choosing the participating troupes; translations and subtitles are provided where necessary. Several of the troupes involved will make appearances in Washington this month.

Paradoxically, one of the highlights is not part of the festival proper. Fearing that some participating East Bloc nations would withdraw, the festival disassociated itself from the controversial musical adaptation of George Orwell's "Animal Farm," performed by The National Theater of Great Britain under director Peter Hall. "Animal Farm" is an allegorical novel critical of the Soviet regime. The musical will be performed at the Morris A. Mechanic Theater, Tuesday through June 22, independent of the festival.

Sweden's communal JordCirkus opens the festival Sunday with "Blood and Champagne," based on Gabriel Garcia Marquez's "100 Years of Solitude," plus "The Duel" and "Little Princess," all in English. Its performances at the Baltimore School for the Arts run through June 22.

Martha Clarke's visually delirious "The Garden of Earthly Delights," based on the triptych by Hieronymous Bosch, will be performed by the American Music Theater Group and Lenox Arts Center at Goucher College's Kraushaar Auditorium Wednesday through June 21.

Italian satirists Dario Fo and Franca Rame, who are husband and wife, will appear separately at the festival; Fo performs in Italian with projected subtitles at Peabody Concert Hall Wednesday through June 20; and Rame performs in English June 19 at the Baltimore Museum of Art. (Fo and Rame appear at the Kennedy Center Free Theater Friday and Saturday. Call 254-3600.)

Californian Fred Curchach's one-man musical mystery "The Inquest for Freddy Chicken" makes use of dolls, masks and lights and involves the audience as both suspect and witness, Wednesday through June 21 at the Theater Project.

Beginning next Friday and beyond, the festival offers works by troupes from Brazil, Bulgaria, Canada, Czechoslovakia, Hungary, India, Japan, Northern Ireland and Poland.

Participating Baltimore companies include high-tech wizards, Impossible Theater, doing "Social Amnesia," which recently played Baird Auditorium here; the Arena Players with "Eyes," an original musical; Center Stage's "Playwrights '86" series, featuring three new plays in repertory; and performances by Action Theater, Industrial Strength Theater, Kuumba, Pleasant Living Players, Theater Collective and Freedom Theater Company. Call 301/366-PLAY for information on Baltimore group performances.

Tickets for festival events range from $6 to $25. For complete information, call 301/625-4270.