The government said Thursday that the Tatars that Josef Stalin forcibly deported en masse from their Crimean homeland during World War II are not entitled to an autonomous homeland.

The announcement was a major setback for the ethnic group, whose members have been agitating for a return from what they consider exile in Central Asia to their ancestral lands on the Black Sea.

The report was issued by a commission headed by President Andrei A. Gromyko to study Tatar grievances that was formed after Tatar activists staged an extraordinary 21-hour demonstration in Red Square last summer.