France announced on Thursday it was reducing its troop numbers in the Central African Republic as it gradually hands over to a 8,500-strong UN peacekeeping force brought in to contain a deadly sectarian conflict.

"We are going to begin a first cutback phase in the following days, going from 2,000 to 1,700 men," army spokesman Gilles Jaron said.

France's Operation Sangaris will be reorganised around two zones -- one between the capital Bangui and the central town of Bambari and the other around Kaga Bandoro and Ndele further north -- with the UN mission MINUSCA taking over almost all the responsibility in the east, Jaron said.

France will continue to provide support to the UN as it tackles ex-Seleka extremists, he said.

Seleka, a mainly Muslim rebel alliance, seized power in 2013, after a coup ousted president Francois Bozize and triggered a wave of deadly sectarian violence between the country's Christian and Muslim populations.

France intervened militarily in its former colony in December 2013 after receiving the green light from the United Nations to try and break the spiral of violence.

Sangaris was joined by the MINUSCA and a European Union force of 700 troops.

Together they restored stability in Bangui and some other zones, without bringing peace to the whole country.

Jaron said there had been "widespread appeasement" in CAR.

Since violent clashes in February between UN forces and the ex-Seleka rebels in the eastern mining town of Bria, "we have seen a disengagement and the more radical elements are losing ground", he added.