Villagers in central Mali said six people found dead in a mass grave last month had been arrested by the military three days earlier, an Amnesty International report said on Tuesday.

Axar.az reports citing Reuters.

The grave, uncovered in the Mopti region on March 25, is the latest in a spate of killings and kidnappings ahead of a July presidential election, that rights groups say are being conducted by the army against suspected sympathizers of extremist groups.

The Malian government and military did not respond to repeated requests for comment. The government has acknowledged some abuses by its forces in the past but also rejects many allegations made by rights groups.

"Civilians in Mali are living in fear," said Amnesty International's West Africa researcher Gaetan Mootoo. "We are urging the Malian authorities to investigate reports of enforced disappearances and extrajudicial killings of civilians in the central region."

Extremist insurgents seized control of Mali's northern desert in 2012 before being driven back by a French-led military intervention a year later. They have since regrouped and carried out attacks further south, winning recruits by playing on local grievances.

In Tuesday's report, Amnesty said 65 people had been killed by improvised explosives used by armed groups since the start of the year, raising concerns about the government's ability to conduct presidential elections planned on July 29.

The UN's independent expert on the human rights situation in Mali reported in February that at least 43 people had been victims of "enforced disappearance" by security forces during anti-militant operations between May and June last year.

Mali's opposition SADI party has accused the army of executing seven civilians who had been attending a religious celebration in the village of Nangarabakan in the Segou region.