French troops have begun arriving in the town of Bunia in eastern Congo where hundreds have been killed in weeks of violence.
The French will lead an EU force to bolster peacekeeping efforts
People in Bunia shouted with joy as the troops drove into the town which has been the scene of several reported massacres.
The soldiers are spearheading a 1,400-strong rapid reaction force being deployed under a special mandate from the United Nations to provide security and protect civilians.
The officer in command of the forces told the BBC's Ishbel Matheson that the troops' first priority was to secure the airport.
Four or five UK officers have also arrived to assist in investigating the risks and technical difficulties involved in deploying a multinational force to Bunia, a UN spokesman said.
Our correspondent says the soldiers arrived without warning, and that more are expected to touch down throughout the day.
She says the presence of foreign troops may deter killing in Bunia, but elsewhere in the surrounding countryside in Ituri region the massacres are likely to continue.
The European Union ratified the sending of the force on Thursday - the first time EU peacekeeping troops have been deployed outside Europe.
France, which is experienced in intervening in African trouble spots, will supply about 700 of the peacekeeping troops.
As well as the UK, diplomats say Belgium, Sweden and Ireland may also participate, along with a number of African nations such as South Africa and Senegal.
The Congolese Government has denied that its troops were involved in killings in Ituri over the weekend in which fighters from the majority Lendu community were reported to have slaughtered at least 100 people in a village populated by Hema people.
Relieved residents have been living in terror for months
Tens of thousands of refugees, many of them children, have been fleeing attacks from militia around Bunia, according to Ugandan reports.
Civilians have been arriving in the Congolese town of Beni, 150 kilometres (93 miles) to the south, and their numbers have raised fears of a food crisis there.