The president of Guinea-Bissau, Malam Bacai Sanha, has been admitted to hospital in Paris after becoming seriously ill, the BBC has confirmed.
Mr Sanha was taken to a hospital in Senegal last week where he spent hours in intensive care, before being flown to France at the weekend.
The 64-year-old president of the West African state suffers from diabetes.
Little information is being released about his health in Guinea-Bissau and tension is reportedly growing.
A source in the foreign ministry told Reuters news agency that Mr Sanha had been put into a medical coma during his treatment.
Opposition parties in Bissau have called for a debate on the situation to avoid what they describe as "political turbulence".
The country has endured repeated military coups, assassinations and political unrest since it became independent from Portugal in 1974.
Guinea-Bissau is a significant transit point for drug-smuggling networks taking narcotics from South America to Europe.