UN troops have taken over the peacekeeping mission in Mali from their African counterparts at a ceremony in the capital Bamako.
A ceremony paving the way for the 12,600-strong force took place on Monday in Bamako.
The force will replace the African-led International Support Mission to Mali (AFISMA).
The new mission begins work months after French troops - deployed in January to fight groups affiliated to al-Qaeda in Mali - began their phased withdrawal. France, Mali's former colonial master, will keep up to 1,000 troops in the country.
Defence and security chiefs of nine troop-contributing African countries and UN officials spent Sunday in last-minute talks in Bamako on personnel, equipment and logistics issues ahead of the handover.
Rwandan General Jean-Bosco Kazura, formerly second in command of African Union troops in Sudan's western Darfur region, will lead the UN mission - known as Multidimensional Integrated Stabilization Mission in Mali, MINUSMA.
The mission aims at ensuring stability in the conflict-scarred nation just four weeks ahead of crucial elections.
AFISMA was put in place by the Economic Community of West African States (ECOWAS) to help the Malian government rein in armed groups who had seized large swathes of territory in the north and sought to introduce Islamic law.
Role in elections
Al Jazeera’s James Bays, reporting from Bamako, said that the handover formalities were continuing. He said that only 6,000 of the actual MINUSMA troops were currently in Mali and the rest are to arrive soon.
The new mission will play a key role in presidential polls scheduled for July 28, although the election commission has raised doubts over its ability to stage a free and fair vote at short notice.
The commission's president, Mamadou Diamountani, said this week it would be "extremely difficult" to get up to eight million voting cards to the electorate in a country where 500,000 people have been displaced by conflict.
Mali is trying to complete a democratic transition after a military coup in March 2012 triggered by the Tuareg uprising that sought to take control of the country's north.
The uprising was soon hijacked by al-Qaeda-linked groups, prompting the transitional government to seek help from the international community, particularly from France.
The 10-month of control of northern Mali by al-Qaeda-affiliated groups ended in January with the launching of a French-led military campaign.