The United Nations took over peacekeeping operations Monday in the war-torn Central African Republic, where thousands have been killed in more than 18 months of sectarian violence.

An initial team of 7,600 UN soldiers and police succeeded about 6,500 African Union-led peacekeepers during a ceremony at M'Poko airport in the capital, Bangui.

Slated to eventually number 12,000 troops, the UN force is tasked with restoring peace and order in the country torn by conflict between Muslim Seleka rebels and Christian anti-Balaka militia, said Babacar Gaye, the UN secretary general's special representative in the Central African Republic.

Close to 6,000 African blue helmets are expected to be integrated into the UN force, which will receive continued support from the 2,000 French and 800 other European forces currently deployed in the former French colony.

"We hope the troops will act with force and uproot the belligerent Seleka and anti-Balaka fighters and other harmful groups," a student in Bangui said, speaking on condition of anonymity.

The UN Security Council welcomed the "seamless transition of authority" to the UN peacekeeping mission and stressed that the deployment of UN forces should happen alongside full implementation of the ceasefire agreement signed July 23.

In response to the transition of peacekeeping operations to the UN, the United States said it was reopening its embassy in the Central African Republic.

US Secretary of State John Kerry named diplomat David Brown to serve as the embassy's charge d'affaires two work with the interim government in support of Central African Republic's democratic transition.

The US will bolster its humanitarian aid to the country by 28 million dollars to 145.7 million dollars, Kerry said.

Violence has not abated in the Central African Republic even though President Catherine Samba-Panza in August appointed a senior Seleka leader, Mahamat Kamoun, as prime minister.

Samba-Panza, a Christian, appointed Kamoun, a Muslim, to try to create a more inclusive government.

The Central African Republic has suffered sectarian violence since Seleka overthrew president Francois Bozize, a Christian, in March 2013.