Anti-Balaka fighters in the Central African Republic are trying to "ethnically cleanse Muslims", Amnesty International, the UK-based rights organisation, says in a report that cites first-hand testimonies from victims of the violence in the country's northwest.

The result of the violent attacks is "a Muslim exodus of historic proportions", Joanne Mariner, senior crisis response adviser for Amnesty International, says in the report.

The report, published on Tuesday, also criticises the international community's response to the crisis, noting that the peacekeeping troops have been reluctant to challenge mostly Christian anti-Balaka fighters, and have been slow to protect the Muslim minority.

The report details witness testimonies included that of a boy named Abdul Rahman who told the group that anti-Balaka fighters demanded the Muslim passengers to get out of a lorry he wastravelling in on January 14, and then killed six members of his family, including three women and a toddler.

The UN on Tuesday accused Christian fighters who armed themselves to retaliate against Muslim rebels of contributing to a "climate of complete impunity".

Muslims have accused the French and African peacekeepers of failing to disarm the fighters at the same time they have been actively disarming the mostly Muslim Seleka rebels, who deposed President Francois Bozize in March last year.

French troops on Tuesday seized a large cache of weapons, including anti-tank mines and mortar rounds, from a Christian neighbourhood in the capital Bangui.

The head of the French military mission in the country said that the Christian fighters picking up arms made them "enemies of peace".

'Culture of impunity'

The anti-Balaka [anti-machete] fighters initially