Bujumbura - Burundi's attorney general acknowledged on Thursday that the government buried dozens of suspected rebels who died after attacks on four military bases without notifying their families, but fell short of admitting the existence of mass graves.Human rights groups have accused the Burundi government of trying to hide the extent of the killings during the December 11 attacks by burying bodies in mass graves.Valentin Bagorikunda said that out of 87 people who died, the government buried 58 bodies of suspected rebels. Eight of those killed in the attacks were security officials, he said.He said the 58 were buried in what he called "official graves" in Kanyosha in the south of Bujumbura and Mpanda in the Bubanza province in the west of Burundi.At least 400 people have died in Burundi since April when President Pierre Nkurunziza launched his campaign for a third term in office which many oppose. Nkurunziza was re-elected in July even as Burundi experienced violent street protests, a failed coup, and assassinations.Burundi has had a long history of violence including civil wars and four successful coups. The international community fears that the current turmoil could unravel more than a decade of relative peace.Amnesty International said in January that before-and-after satellite images and video footage clearly show five possible mass graves in the Buringa area on the outskirts of Bujumbura."The imagery, dating from late December and early January, shows disturbed earth consistent with witness accounts," Amnesty said in a statement.Witnesses have said the graves were dug on the afternoon of December 11 in the immediate aftermath "of the bloodiest day of Burundi's escalating crisis," it added."These images suggest a deliberate effort by the authorities to cover up the extent of the killings by their security forces and to prevent the full truth from coming out," said Muthoni Wanyeki, Amnesty International's Regional Director for East Africa, the Horn and the Great Lakes.Bagorikunda declined to answer questions on Amnesty's claim.