MINNEAPOLIS (AP) _ A young Moscow actress apparently defected shortly before her children's theater troupe went home Monday after performing as part of an exchange program with a local group, a Minneapolis theater official said.

Larisa Firsova of the Central Children's Theatre of Moscow didn't show up Monday morning as 34 members of the 46-member troupe assembled at their hotel to head for the airport, said Bill Conner, executive director of the Children's Theater Company of Minneapolis. ''It was quite a surprise,'' Conner said.

Conner said FBI officials told him that Firsova, a 24-year-old apprentice actress, had gone to them in the middle of the night and that they took her to talk to Immigration and Naturalization Service officials.

He said INS officials wouldn't allow anyone to talk to her.

''We have no sense of what her status is. They (the FBI) made it clear they don't know, either,'' said Conner, adding that he could assume only that Firsova has defected.

FBI officials did not immediately return a phone call seeking comment, and there was no answer at the local INS office.

Conner said he had no indication that Firsova, who appeared to be happy, would defect. The actress has a husband in Moscow, he said.

Firsova had one of the chorus roles in ''Dream To Be Continued,'' which finished its eight-performance run Sunday in St. Paul.

The 34 troupe members returned home as planned Monday. The remaining 11 plan to stay a few more days to work on a play that the Moscow company's artistic director, Alexei Borodin, plans to direct in Minneapolis this summer, Conner said.