HELSINKI, Finland (AP) _ Opera singer Martti Talvela, whose deep bass voice and tall stature were famous in the title role in ''Boris Godunov,'' has died of a heart attack, newspapers reported today. He was 54.

The reports said Talvela, who often performed at the Metropolitan Opera in New York, died Saturday night while celebrating a daughter's wedding at his farm in Juva, about 150 miles northeast of the capital.

Newspapers reported, without quoting sources, that Talvela died of a heart attack shortly after dancing with his newly married youngest daughter.

Officials at the Savonlinna Opera Festival today declined to comment on his cause of death and said his family also was refusing comment on funeral arrangements.

The festival on Sunday was interrupted by an announcement of his death. The festival's artistic director, Walton Gronroos, said the father figure of Finnish opera had died.

Talvela was artistic director of the festival in eastern Finland from 1972 to 1979, which he elevated to a major international opera event.

Two months ago he agreed to become the director of the Finnish National Opera in 1992.

Roger Lindberg, a member of the committee to select a new director, described Talvela's unexpected death as a ''catastrophe'' for the National Opera and said ''it will be very difficult to find a suitable new director.''

Talvela, born Feb. 4, 1935, began his international career in 1960 and was acclaimed in major opera centers for his powerful bass voice. He also recorded extensively.

The singer is survived by his wife, Anukka, and three children.