FRANCE will increase its force in the Central African Republic (CAR) to at least 1000 soldiers after a UN resolution expected next week as French warned of the risk of regional instability.

The landlocked nation of 4.6 million people has descended into violence since rebels, ousted President Francois Bozize in March.

Foreign Minister Laurent Fabius said: "We are going to reinforce our presence. If the (power) vacuum and implosion sets in, it will threaten all countries in the region: Chad, Sudan, Congo and Cameroon."

French Defence Minister Jean-Yves Le Drian said the mission was likely to last about six months depending on the timetable set by the UN.

He dismissed comparisons with France's intervention in Mali, where Paris deployed 4000 troops in January to keep Islamist militants from taking the capital Bamako.

French UN Ambassador Gerard Araud said French troops in CAR would restore law and order until an African Union force of 3600 troops - known as MISCA - was fully operational.

The move comes after after a top UN official warned of mass atrocities and possible civil war in CAR.

Deputy Secretary-General Jan Eliasson told the UN Security Council the situation in the country was deteriorating rapidly. He warned that the country was becoming "a breeding ground for extremists and armed groups" and never-before-seen sectarian violence between Muslims and Christians, and that a UN peacekeeping force may soon be the only option.

Mr Eliasson said virtually the entire population is "enduring suffering beyond imagination," and a third of the people are "in dire need of food, protection, health care, water, sanitation and shelter".

Mesmin Dembassa Worogagoi, CAR's charge d'affaires to the UN, said "people aspire to one thing alone - peace and security," and UN support was essential to achieve this.