The difficult waters of Ivory Coast politics became even more turbulent on Monday as Vice President Daniel Kablan Duncan quit, five days after the sudden death of Prime Minister Amadou Gon Coulibaly, and with crucial elections less than four months away.

Kablan Duncan, 77, handed in his resignation in February on "personal grounds", which President Alassane Ouattara accepted last week, the president's office said in a statement read by chief of staff Patrick Achi.

Rumours that Kablan Duncan would be leaving office have circulated for several days.

He has traditionally been seen as close to Ouattara, even though he is a member of the PDCI -- a party that was once part of the president's political alliance before it joined the opposition.

Kablan Duncan served as foreign minister from 2011-12 and then as prime minister in charge of economy and finance from 2012-17.

In January 2017, he became the first vice president in Ivory Coast's history, taking up a post created under a new constitution adopted in 2016.

Ouattara "would like to pay tribute to a great servant of the state, a man of power and commitment," the statement added.

Political commentators dismissed the idea that Kablan Duncan had stepped down for personal reasons and suggested he had been unhappy for some time.

"He was fed up, fed up with constantly being put down" in the government's pecking order, said a senior member of the PDCI.  

Coulibaly shock 

His departure was announced just five days after the sudden death of Coulibaly, 61, a popular figure seen as Ouattara's anointed successor for elections due on October 31.

Coulibaly had just returned to Ivory Coast after a two-month stay in France, where he received treatment for chronic heart problems. 

One of the world's major coffee and cocoa producers, Ivory Coast still carries the scars of a brief civil war that erupted nearly a decade ago.

In 2011, Ouattara, at the head of a rebel force based in the Muslim-majority north of the country, ousted the then-president, Laurent Gbagbo, who refused to leave office after losing long-delayed elections. 

The months-long standoff claimed some 3,000 lives and dug a division across the country.

Coulibaly, the frontrunner in the elections, was expected to play a central part in Ouattara's strategy of stabilisation.

An emerging option for Ouattara, 78, is that he may seek to run again -- a choice that could spark accusations of abuse of democracy under the country's two-term presidential limits.

In March, he decided against seeking a third term in office, but has previously argued that the constitutional change reset the clock, enabling him to do so. 

Another option is Defence Minister Hamed Bakayoko, who stood in for Coulibaly while he was abroad for medical treatment, said political analyst Jean Alobro.

"All options are on the table, including a new candidacy for President Ouattara," the executive director of Ouattara's RDHP party, Adama Bictogo, said last week.

He added that he did not expect anything to be announced before Coulibaly's funeral.

After eight days of national mourning, which began last Friday, Coulibaly will be buried in his home town Korhogo, in the north of the country.

Gbagbo question

Another question mark lies over the future of Gbagbo, who was cleared last year at the International Criminal Court (ICC) of crimes against humanity, a ruling that prosecutors are appealing. 

His party, the Ivorian Popular Front (FPI), wants Ouattara to come home and engage in a "dialogue".

"The regime is clearly in a state of crisis... it's completely in shreds," former prime minister Pascal Affi NGuessan, an FPI heavyweight, said on Monday.

Gbagbo technically faces being jailed on his return after being sentenced in absentia to a 20-year term last November for the "looting" of the local branch of the Central Bank of the West African States (BCEAO) during the post-election crisis.