Doctors Without Borders (MSF) on Wednesday denounced the "unprecedented" violence in the Central African Republic, urging all sides to respect civilian safety and calling for urgent international aid.

"Tens of thousands of villagers have fled a fresh wave of attacks summary executions, perpetrated both by armed groups and government forces in the northwest of the country," the NGO said.

People were taking refugee in the brush, without protection and particularly exposed to the dangers of malaria, the biggest cause of death in the country, MSF said in its report.

Hygiene conditions are "disastrous" with so many families living together, Ellen Van der Velden, head of the MSF mission in the Central African Republic said in the statement.

"MSF is today one of the only NGOs working in the conflict zones. It provides medical and surgical help, access to drinking water and hygiene s well as nutritional help. But greater aid is needed," the Geneva-based group said.

Other humanitarian groups have left the country or suffered from robberies and now need to "re-equip and find sufficient funding," MSF official Dr Andre Munger told AFP.

Last month the UN's children's agency decried the total lawlessness in the country, which has "spelt disaster for children."

CAR was plunged into chaos in March when president Francois Bozize was toppled by rebels.

Since then swathes of the country has fallen into the hands of armed gangs and foreign mercenaries, with the unrest threatening to explode into a conflict between the Christian majority and Muslims.

French Foreign Minister Laurent Fabius on Sunday pledged to send more troops to the country but also warned the coup leader there to stick to his own promise of free polls in early 2015.

Western powers have reluctantly recognised President Michel Djotodia, the leader of the now disbanded Seleka rebel group that toppled Bozize as the country's first Muslim president.

In exchange, Djotodia has formed an inclusive government and pledged not to run in elections due to mark the end of an 18-month interim period in early 2015.

The impoverished landlocked country is a little larger than France but sparsely populated and Djotodia is facing the same difficulty as his predecessors in extending his authority beyond the capital.

Chaos followed Bozize's ouster and reports of widespread summary executions, looting and abuses against civilians spurred the international community into action.

Former Seleka commanders gone rogue have established mini-fiefdoms scattered across the country in which they sew terror.

In some areas, villagers have responded by forming vigilantes, some of which have specifically targeted Muslims.