There was a storm over Abidjan early in the day, but it was unclear whether heavy weather had played a role in the Antonov aircraft going down.
A French military source said the plane was chartered as part of anti-jihadist Operation Barkhane, under which France maintains a 4,000-man mission in the region.
The operation aims to shore up fragile Sahel countries against Islamists who have carried out a wave of bloody bombings, shootings and kidnappings.
Four French nationals and two Moldovans were hurt, the French military source said, adding that three of the French injured are soldiers.
“There were 10 people on board, Moldovans and French people. The four victims who died are Moldovan nationals,” firefighter Colonel Issa Sakho told local television.
The plane had taken off from Ouagadougou in Burkina Faso and crash-landed in the sea near Abidjan, breaking in half, he said.
Local forces were hoping to secure the wreck before it drifted away “so investigators can do their job”, he said.
The wreck could be seen from the beach, where hundreds of onlookers gathered after the crash, an AFP reporter said.
– ‘Bodies in the water’ –
The French military base in Abidjan provides logistical support for the operation which is headquartered in N’Djamena, the capital of Chad. French special forces are stationed in Ouagadougou.
Every year, around 100 sorties are flown out of Abidjan airport as part of Barkhane, often by former Soviet army pilots in Ukrainian-made Antonovs.
The planes frequently carry French military personnel and sub-contractors accompanying their cargo.
James Mobioh Aka, a rescue worker based near the airport, said he received a call around 0600 or 06030 GMT saying an aircraft had crashed in the sea.
“When we arrived, we saw the plane, and we saw there were bodies in the water,” he said. “One young man went into the water, another followed, and they recovered three.”
The fourth body was found further along the coast.
France keeps around 950 military personnel in Ivory Coast as part of a contingent based in the biggest French army base on Africa’s Atlantic coast. Other bases are in Libreville, Gabon, Dakar and Senegal.
One of their key missions is to extract French or other western civilians in case of trouble in Ivory Coast or neighbouring countries.
Abidjan is strategically well-placed in the region as most French-speaking African countries can be reached by air in under three hours.
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