"Four Muslims were killed Thursday morning" by Christian militia fighters, and "three people died" in a separate attack by the Union for Peace in CAR (UPC), a UN source said.

A priest was among those who died in the clashes, and another has been missing since, according to a church source in Bangui.

Vladimir Monteiro, spokesman for the UN peacekeeping mission Minusca, also confirmed the incidents, telling AFP that Christian militiamen known as anti-balaka had killed Muslims and an hour later, "the UPC responded by attacking a camp for displaced people" in Alindao.

The church of Alindao and a part of the camp were burnt, he added.

"Part of the population fled. Hundreds of displaced people have found shelter at Minusca's forward operating base" in the region.

Long a UPC stronghold, Alindao has witnessed chronic fighting in recent months that has also killed two UN soldiers and a humanitarian aid worker.

One of the world's poorest nations despite a rich supply of diamonds and uranium,the CAR has struggled to recover from a 2013 civil war that erupted when President Francois Bozize, a Christian, was overthrown by mainly Muslim Seleka rebels.

Since then, the country of 4.5 million people has been blighted by simmering sectarian violence which has killed thousands.