Prime Minister Andranik Margaryan of Armenia has died of a heart attack at the age of 55, officials in the Caucasus former Soviet republic say.
Mr Margaryan, a dissident in Soviet times, became prime minister in May 2000 and was also the chairman of the governing Republican Party.
President Robert Kocharyan has called emergency talks over his death later on Sunday, the party's news service says.
The late premier had heart surgery in 1999, one Armenian report said.
He is survived by two daughters and a son.
Born in the Armenian capital Yerevan in 1951, Andranik Margaryan studied cybernetics and graduated as a computer engineer.
An Armenian nationalist and critic of the Soviet system, he was jailed for two years in 1974 for his propaganda work and political activism, his official biography notes.
During the Armenian-Azerbaijani conflict over Nagorno-Karabakh in the early 1990s, he actively supported the Armenian side and took part in combat, according to his party's website.
He was appointed prime minister shortly after the October 1999 assault on parliament in which Prime Minister Vazgen Sarkisyan and six others were killed by Armenian extreme nationalists.