Behind a downtown storefront, one of Washington's small experimental companies has staged a three-character play that becomes a searing experience in the theater.

"Statements After an Arrest Under the Immorality Act" is a shattering picture of life in South Africa's apartheid society, depicted as non-discriminatory in only one way -- it robs blacks and whites alike of self-respect, personal dignity, and humanity.

"Statements," -- staged by the Source Theatre Company in association with the Independent Theatre Project -- was written by Athol Fugard, the white South African playwright whose works include "The Blood Knot" and "Sizwe Banze Is Dead." He has created a biting indictment of apartheid; but it is more than that. It is also the poignant tragedy of two people: Errol Philander, a black teacher, and Frieda Joubert, a white librarian who lives a lonely existence.

Their tenderness and love cannot survive the fear and hate of apartheid which come between them. Frieda cannot understand Philander's rages and bitterness. They fear the light and the sound of a footstep as they lie on the rug in the library's office in secret tryst.

And after their arrest under South Africa's immorality act, both Frieda and Philander are coerced by fear to try to explain away the one relationship that gave meaning to both their lives.

Philander, who has taught his black pupils to scrawl "proud" on the blackboard, must cringe and plead for his life, Frieda wavers from terror to defiance.

We first meet the lovers as they lie amid rumpled bed sheets on the floor in the library's office. As they talk and move about, the sheets are dropped casually and their nakedness on stage becomes quite natural for the remainder of the one-act-play.

Cliff McMullen and Janet Stanford give moving, powerful performances as Philander and Frieda (and both have mastered a splended South African accent). McMullen captures both the exuberance and rage of Philander, who must sneak into town from the blacks' "location" to see Frieda. Despite his education and experiences, "whatever happens, I'll be walking back to it," he says.

Frieda, who first saw her lover as a "colored man at the rear door asking for books -- and then came to forget Philander's color -- is poignantly played by Stanford. In one scene, she plays both Frieda and her inquisitor, and marvelously catches the prurient curiosity of the interrogator.

Chris Legg gives the right touch of cold hate to his narration as the white South African policeman who arrests the lovers.

The director, Kim Peter Kovac, is resourceful and imaginative in staging the 50-seat theater loft. As the police make their raid and take pictures, strobe lights flash and Frieda and Philander are caught in quick-freeze takes.

"Statements . . ." will be performed at 7 this evening and 8 p.m. tomorrow and Sunday at the Washington Project for the Arts, 1227 G St. NW.