Up to 10 new mass graves have been discovered near the site of a July attack on a camp for displaced people, officials said Tuesday, amid allegations that initial casualty totals were downplayed to mask killings carried out by the national army.

Rights groups claim summary executions were carried out by the Republican Forces of Ivory Coast, known by its French acronym of FRCI. Last month, officials found six bodies in a well close to the former campsite in the western town of Duekoue.

Government, army and U.N. officials toured 10 more graves in the same area on Saturday, said Paul Mondouho, vice-mayor of Duekoue. He said the graves had first been identified by civilians, and that officials did not know the number of bodies they contained because they had not yet been properly exhumed.

"People were suspecting the presence of bodies in these graves because of the smell coming out of them and because of the shoes we saw nearby," Mondouho said.

Prosecutor Noel Dje Enrike Yahau, who is based in the commercial capital of Abidjan, confirmed that multiple new graves had been discovered but could not provide details. U.N. officials and the local prosecutor in charge of investigating the suspected killings could not be reached Tuesday.

U.N. spokeswoman Sylvie van den Wildenberg confirmed that U.N. forces helped Ivorian authorities secure a perimeter around 10 wells "similar to the one in which six bodies were found," and that "some of those wells are suspected mass graves."

She stressed that Ivorian authorities were leading the investigation but that the U.N. was able to provide assistance.

Army spokesmen could not be reached Tuesday. The Justice Ministry has previously vowed to investigate the discovery of the initial grave.

On the morning of July 20, a mob descended on the U.N.-guarded Nahibly camp, which housed 4,500 people displaced by violence in Ivory Coast, burning most of the camp to the ground. Officials said at the time that six people were killed.

The attack was prompted by the shooting deaths of four men and one woman on the night of July 19, according to local officials and residents. In response a mob of some 300 people overran the camp on the morning of July 20 after the perpetrators of the shootings reportedly fled there.

The victims in the July 19 attack lived in a district dominated by the Malinke ethnic group, which largely supported President Alassane Ouattara in the disputed November 2010 election. The camp primarily housed members of the Guere ethnic group, which largely supported former President Laurent Gbagbo.

Gbagbo's refusal to cede office despite losing the election to Ouattara sparked months of violence that claimed at least 3,000 lives.

Albert Koenders, the top U.N. envoy to Ivory Coast, said one week after the attack that U.N. security forces had been inside and outside the camp at the time but that no Ivorian security forces were present. He said the U.N. forces decided not to fire at a large group of people that were attacking the camp in order to avoid "a massacre."

Several witnesses have said soldiers and traditional hunters, known as dozos, participated in the attack on the camp. Both military and dozo leaders have denied the claims, saying they had tried to protect the camp.

In a statement released Friday, the International Federation for Human Rights, known by its French acronym of FIDH, said it had information — including the preliminary results of autopsies — confirming that the six bodies found in October were men who had been summarily executed by the army.

"The disappearance of dozens of displaced persons after the attack, as well as confirmation of cases of summary and extra-judicial executions, suggest a much higher victim rate than the official figures report," said the organization, which counts Ivorian civil society groups among its members.

Duekoue was one of the hardest-hit towns during the post-election violence. The U.N. has established that at least 505 people were killed in and around the town, including during a notorious March 2011 massacre that claimed hundreds of lives and was allegedly carried out by fighters loyal to Ouattara.

Duekoue residents belonging to ethnic groups that supported Gbagbo have long complained about abuses carried out by the FRCI, with some pointing to the direct involvement of the local commander, Kone Daouda. FIDH said in its statement that Daouda had been transferred following the discovery of the grave in October, and called for him to be interrogated over the matter.

The group also said two FRCI members were being "actively sought" after failing to return to their barracks on Oct. 16, noting that they are believed to have fled to neighboring Burkina Faso.