The discovery of the mass grave is a grisly reminder of the Ivory Coast's deadly violence last month. [AFP]

United Nations investigators have discovered at least 68 bodies in a mass grave in a soccer field in the Ivory Coast's commercial capital, the Associated Press news agency reported.

The bodies discovered in Abidjan were probably of those killed last month by forces loyal to the deposed president Laurent Gbagbo, Guillaume Ngefa, a deputy director of the UN mission in the Ivorian city, said on Monday.

Investigators visited and photographed the site on Friday after speaking to witnesses and interviewing family members to identify the bodies, Ngefa said.

Abidjan saw heavy fighting between forces loyal to Alassane Ouattara, the incumbent president and those of Gbagbo on April 12, a day after the former strongman was arrested by Ouattara followers.

Gbagbo had refused to hand over power after losing the 2010 elections - an act that nearly plunged the country into a civil war.

Yopougon, where the soccer field is located, is believed to be where Gbagbo's forces took cover after their leader's fall.

The area has historically been a Gbagbo stronghold, but it has pockets inhabited by the Djola and Baole, ethnic groups that voted for Ouattara in November's divisive election.

Mass graves

The victims were almost exclusively from these two groups, witnesses told the Associated Press.

Ngefa said the largest grave is believed to hold 31 bodies; another has at least 21.

Click here for more of Al Jazeera's special coverage

The killings may have been in revenge for the arrest of several dozen militiamen who had taken cover inside a Baptist Church in Yopougon, said Ngefa.

The militiamen were rounded up by Ouattara's army. Soon after, pro-Gbago gunmen began going door to door in Yopougon, arresting and killing perceived supporters of Ouattara, Ngefa said.

Gbagbo's refusal to cede power after losing the November election in Ivory Coast sent the West African nation into a spiral of violence.

More than 1,000 civilians were killed, first by the army controlled by Gbagbo and later by a former rebel group allied with Ouattara that seized control of the country and toppled Gbagbo.

Monday's announcement of the grisly discovery comes on the same day as the Ivory Coast, the world's largest cocoa producer, exported its first shipment of cocoa beans in several months.

Exportation was normalised after Ouattara took oath last week as the country's democratically elected president, bringing stability to the African country that had been plagued by lingering infighting.

Source: AP