A U.S. operation to airlift some 850 Burundians into the Central African Republic to help restore security to the strife-torn nation should be completed this week, a top U.S. official said Tuesday.

Washington also welcomed Belgian plans to send up to 150 troops to join a French and African Union (AU) force, and revealed that it had a few American troops on the ground in Bangui to help with the airlift.

French Foreign Minister Laurent Fabius announced Tuesday that other European countries would deploy ground troops to the violence-hit Central African Republic, without identifying them.

"We will soon have troops on the ground provided by our European colleagues," he told the lower house National Assembly, days after he decided to seek help from Europe in its former colony, where France has deployed a 1,600-strong force to quell deadly sectarian violence.

Some 210,000 people have been uprooted from their homes by violence in the Central African Republic capital in the past two weeks alone, the United Nations said Tuesday.

"The situation is very serious and appears to be worsening," U.N. refugee agency spokesman Adrian Edwards told AFP.

France voiced concern on Monday over the firing of three ministers in the Central African Republic's transitional government, saying the move risks causing more instability in the strife-torn country.

President Francois Hollande meanwhile said France's decision to deploy 1,600 troops in its chaotic former colony was aimed at stopping "crimes against humanity".

France's foreign minister will ask his European counterparts Monday for more help in the Central African Republic, where a French-backed military force is trying to quell deadly sectarian violence.

"Tomorrow I will go to the Foreign Affairs Council (in Brussels) and I will ask that there be more solid, stronger support," Laurent Fabius said Sunday on Europe 1 radio.

France warned Friday of a dangerous spiral of sectarian violence in the Central African Republic as the U.N. said more than 600 people had died in recent unrest.

French Defense Minister Jean-Yves Le Drian flew into the capital Bangui early Friday and met some of the 1,600 French troops deployed in the country before he was due to hold talks with CAR's interim authorities.

French Defense Minister Jean-Yves Le Drian on Friday arrived in the Central African Republic for talks with the interim leaders of the strife-torn nation, where Paris deployed troops last week, according to an aide.

The visit comes on the heels of that by President Francois Hollande, who stopped in the country on Tuesday after attending Nelson Mandela's memorial in South Africa.

French President Francois Hollande called Thursday for a "permanent European fund" to finance emergency interventions in crises such as the situation in the Central African Republic.

Hollande said he would request the fund, which would be used before peacekeeping operations are in place in crisis zones, during next week's European Council meeting in Brussels.

French President Francois Hollande said on Thursday that security was gradually returning to Central African Republic (CAR), where France has deployed 1,600 troops to stem sectarian violence.

"The night (in the capital Bangui) was calm... But we must be very vigilant, cautious and carry out the disarmament (of militias) to the end," said Hollande, who earlier this week paid a swift visit to the former French colony.

The U.S. military flew Thursday the first batch of troops from Burundi to join an African Union force to restore security in the Central African Republic, the army said.

"The first U.S. aircraft to transport the Burundian contingent to Bangui arrived this morning," said Lieutenant-Colonel Potien Hakizimana, commander of the 850-strong Burundi battalion going to CAR.