The United States’ military has begun flying Rwandan troops into the Central African Republic Thursday in its second such operation in support the African Union's efforts to stem bloodshed there.

A US official, speaking to Reuters Wednesday on condition of anonymity, said the airlift operation could last just over a month and would involve two US military C-17 aircraft.

The airlift mission would be very similar to the one the United States carried out flying forces from Burundi into the Central African Republic late last year, the official said.

Rwanda's foreign minister has been quoted telling local radio that the country would send around 800 troops.

A Muslim rebel coalition, Seleka, seized power in Central African Republic last spring, unleashing a wave of killings and looting that in turn sparked revenge attacks by the "anti-balaka" Christian militia.

The United Nations estimates that months of fighting in the landlocked former French colony has displaced around 1 million people, or just over a fifth of the population.

The national death toll is difficult to estimate. More than 1,000 people were killed in Bangui alone last month and sporadic violence has continued despite the presence of 1,600 French troops and 4,000 African Union peacekeepers.

France's UN envoy said on Wednesday that the level of hatred in Central African Republic between Muslims and Christians had been underestimated and is creating a "nearly impossible" situation for African Union and French forces to combat.

READ: Is interventionist France able to halt CAR’s drift to anarchy?

UN Secretary-General Ban Ki-moon is expected to submit a report to the Security Council next month with recommendations for a possible UN peacekeeping force that would take over from the African troops.