Article published on the 2009-06-08 Latest update 2009-06-08 18:31 TU
Bongo was undergoing medical treatment in a private clinic in Spain for what some sources say was intestinal cancer.
The 73-year-old leader, who has ruled the former French colony since 1967, checked into the clinic on 21 May and several sources said the disease had entered an advanced stage.
In early May, Bongo had announced that he was temporarily suspending his duties in order to rest and mourn the death of his wife, Edith Lucie Bongo Odimba.
There had been rumours since Sunday evening that the head of state was dead. However Gabonese authorities had denied the rumors and said Gabon would lodge a formal protest with the French government to complain of the "repeated excesses of the French press" in reports concerning Bongo's health.
Experts on Gabon say that foul play cannot be ruled out in Bongo's death. Douglas Yates, Professor of Political Science at the American University of Paris, told RFI that "the succession of Omar Bongo has led to a kind of palace politics", referring to the number of Bongo's family members involved in both domestic and international politics.
Monday afternoon, Gabonese Prime Minister Jean Eyeghe Ndong confirmed President Bongo's death, adding that the country would observe a 30 day period of mourning, during which all flags will be flown at half mast.
Prime Minister Ndong called on the Gabonese people to "remain united and stand together in contemplation and dignity".
Bongo led Gabon for over 40 years, since December 1967, when he was 31.
Bongo was a political ally of a number of French presidents, including Charles de Gaulle, François Mitterand, and Nicolas Sarkozy, who stopped in Libreville on his first presidential tour of Africa in 2007.
However, this past winter, Bongo's government accused France of trying to "destabilise" Gabon. It was a response to a French court decision to freeze Bongo's bank accounts after France conducted an inquiry into luxury properties he had bought there. Anti-corruption activists had said embezzled state funds were used to pay for those properties.
In 2003, a trial in Paris revealed widespread corruption in the oil industry in Gabon.
Oil provides a large portion of Gabon's income. In the 1960s, it became the first state to host French oil giant Elf. The company served as a base for French military and espionage activities in Africa.
President Omar Bongo dies at 73