Amadou Gon Coulibaly, Ivory Coast's prime minister and the ruling party's candidate for an October presidential election, died on Wednesday, President Alassane Ouattara said.

The 61-year-old Gon Coulibaly, who had heart surgery in 2012, became unwell during a weekly cabinet meeting and was evacuated to a hospital where he passed away, Ouattara said in a statement read on national television.

Gon Coulibaly had returned to Ivory Coast last Thursday after two months in France to undergo a heart exam and rest.

"Fellow compatriots, Ivory Coast is mourning. It is with deep pain that I announce to you that Prime Minister Amadou Gon Coulibaly has left us," Ouattara said in a statement read by the presidency's secretary general.

Gon Coulibaly's death is likely to set off a scramble within the ruling RHDP party to replace him as its candidate in an election that is considered a key test of stability for the world's top cocoa producer.

Ouattara's first win in 2010 over incumbent Laurent Gbagbo sparked a brief civil war in which about 3,000 people died, and political tensions have been rising ahead of October's poll.

Ouattara designated Gon Coulibaly as the RHDP candidate in March after announcing that he would not seek a third term.