Guinea Bissau President Malam Bacai Sanha died on Monday in a Paris hospital, his office said, raising fears of a fresh power struggle in the chaotic West African state.
Sanha had been in poor health since coming to power in 2009 and left Guinea Bissau in late November for treatment abroad.
The U.S. embassy in Dakar warned its citizens last month that there was an increased potential for political instability and civil unrest as a result of Sanha's ill-health. The coastal state is notorious as a stopoff for cocaine being smuggled into Europe from South America.
With pain and sadness, the president's office reports to the people of Guinea Bissau and to the international community the death of His Excellency the President, Malam Bacai Sanha, this morning, January 9, at Val de Grace Hospital where he was being treated, the statement said.
It did not disclose the cause of death but the 64-year-old was believed to be suffering from diabetes, and a foreign ministry source told Reuters he was placed in an artificial coma during his treatment in Paris.
Sanha's death could spark unrest in a state that has seen four coups since independence from Portugal in 1974, along with countless failed coup attempts.
(Sanha's) death worries me a great deal because we know there are many bad people who want to take over power at all costs, said Souleymane Sadio, a Bissau resident.
Over the last few years U.S. and European intelligence and security services have focused more attention on West Africa's Atlantic seaboard to head off problems of cocaine-trafficking, illegal migrant flows and the southward creep of militant Islam.
Gunfire erupted in the capital, Bissau, on December 26, killing two people, in what the government called a foiled coup but which security and diplomatic sources said may have been a clash between rival military factions over drugs.
New elections to replace Sanha must be held within 90 days according to the constitution, and are likely to pit Prime Minister Carlos Gomes Junior against rivals, including former president Kumba Yala, who enjoys support from fellow ethnic Balanta in the military.
President of the National Assembly Raimundo Pereira is meant to act as interim president during the transition.
Gomes has effectively been running the country since Sanha's departure and has managed to draw millions of dollars in donor support from Angola for army reform while also winning allies in the military, including army chief General Antonio Indjai.
He has promised to fight drugs trafficking, though his opponents have accused him of being complicit in recent deals.
This new step in (Gomes') growing hegemony might induce some radicals into action, but my guess is he has a very strong hand right now, said Vincent Foucher, an analyst at International Crisis Group in Dakar.
(Writing and additional reporting by Richard Valdmanis; Editing by Ben Harding)