LAGOS, Nigeria (AP) — Amnesty International opened an office Tuesday in Nigeria, promising to investigate allegations of abuses from oil pollution and forced evictions to charges of military killings of civilians in the fight against Boko Haram Islamic extremists.

"From the relatives of the thousands killed and missing in northeast Nigeria to the thousands of villagers in the Niger Delta who cannot plant crops or drink clean water because of oil pollution, Amnesty International will stand in solidarity with all the people in Nigeria who face human rights violations and abuses," said the director of the office in Abuja, the capital, veteran Nigerian career diplomat M.K. Ibrahim.

Nigeria's new government invited the London-based human rights group into the country, Ibrahim told the AP, after its report accusing Nigeria's military of killing some 800 civilian detainees by shooting, torture, starvation and suffocation. Amnesty named five senior officers it said should be tried for war crimes in its March report.

The Associated Press has reported the deaths of some 3,000 people in military detention within a matter of months in 2013, and the shootings of hundreds of unarmed detainees freed from a barracks in northeastern Maiduguri in a Boko Haram attack last year.

Amnesty had a combative relationship with the previous Nigerian government, headed by Goodluck Jonathan, which denied allegations of gross military abuses.

But Buhari, who won elections that brought the West African oil producer its first democratic change of government, has promised to investigate the charges. Buhari told Amnesty that the investigation can start only after the appointment of a justice minister and attorney general, expected in coming weeks, said Ibrahim.

One of Buhari's first acts after his May 30 inauguration was to fire all the military chiefs.