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

French Defence 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 the country's interim authorities.

His arrival came amid continued unrest in the capital, where residents reported seeing bands of armed thugs roaming the streets and hearing heavy bursts of gunfire in some neighbourhoods.

UN refugee agency UNHCR said that more than 600 people had been killed in the violence in CAR in the past week, including 450 in Bangui and 160 in other parts of the country.

It said the death toll was likely to rise as new bodies were found.

"The spiral of confrontation has abruptly worsened," Le Drian said in a speech to about 200 French soldiers in Bangui, also warning of "the early beginnings of a humanitarian crisis".

Concerns have been growing over the humanitarian situation in the impoverished country, which was plunged into chaos after a rebel-backed coup ousted president Francois Bozize in March.

France sent troops into its ex-colony at the weekend to bolster an African peacekeeping force that has struggled to contain increasing violence, including sectarian clashes between Christians and Muslims.

Le Drian said he was in the country to offer "the support of a proud nation" to French troops, who suffered their first losses when two soldiers were killed in clashes on Monday.

UNHCR said the violence had forced nearly 160,000 residents of Bangui from their homes in the past week. They were spread over some 40 sites, including in camps, churches and mosques.

Many were living rough, their misery compounded by recent downpours.

At a camp of 45,000 displaced people by Bangui airport, the distribution of food on Friday turned violent with the plundering of rations of rice, oil and beans.

"It's four days since my three children and I have had anything to eat," said Jean-Marie Namesene, 41, a civil servant who managed to get his portion before the looting began. "Thank you, thank you to the people who did this."

Others were not so lucky.

"I've been waiting for six hours, no one lets me pass," said Yvette Kimina, a 32-year-old with three children, while another desperate woman in the queue stood breastfeeding her baby.

French troops 'impartial'

Meanwhile, Le Drian was to meet later Friday with interim president Michel Djotodia, the former leader of the now disbanded Seleka rebel coalition that ousted Bozize.

Djotodia became the first Muslim president of the majority Christian country following the coup, but while some Seleka members remained loyal, others started spreading terror which government forces could not stop.

Months of massacres, rapes and looting followed, with locals forming Christian vigilante groups in response.

The UN's human rights office said that 27 Muslims had been killed by militia in one village and raised concerns about "retaliatory attacks between Christians and Muslim communities".

"We are alarmed at the increasing tensions among religious communities," said Ravina Shamdasani, spokeswoman for the UN high commissioner for human rights.

Prime Minister Nicolas Tiangaye told France 24 television he regretted that "religious communities that had always lived together in perfect harmony are now massacring each other."

Le Drian responded to accusations from the Muslim community that France favoured the country's Christians, insisting that French troops "will be impartial to the end" and were "very conscious of the importance of their mission."

Despite some signs of life returning to normal, the situation remained extremely tense in parts of Bangui.

Heavy exchanges of gunfire were heard early Friday in the western neighbourhood of Miskine, residents said.

"It was horrible. There was firing everywhere," said one resident, who gave her name only as Jennifer.

In downtown Bangui however, banks were reopening and petrol stations were operating for the second day running.

Long queues formed as taxi drivers returned to the streets and residents filled up on kerosene for the generators often used in a city that suffers from frequent power cuts.

"It is my first day at work since December 5," said taxi driver Theodore Jusalin. "There are errands to run. People are starting to go out, to go to work."

Humanitarian groups have urged the United Nations to do more to provide desperately needed aid to Bangui and on Friday UN children's agency UNICEF said it was sending a major airlift of supplies to the capital.