The UN Security Council will vote Thursday on a measure authorizing thousands of African and French troops to end anarchy in the Central African Republic, where massacres have led to warnings of genocide-style strife.
As the council prepared for the vote, shots rang out early Thursday and blasts from heavy weapons rocked several districts of the Central African capital.
The automatic gunfire whose origin was not immediately clear started around 5:30 am (0430 GMT) in the north of Bangui and then spread to other neighbourhoods not far from the city centre.
The UN resolution, which envoys say is certain to be passed unanimously, also orders an arms embargo against the huge, impoverished nation where chaos has reigned since rebels forced the president to flee in March.
Muslim and Christian groups are fighting each other and tens of thousands of people have taken refuge in churches and mosques fearing sectarian attacks, according to aid workers.
The draft resolution highlights the "total breakdown in law and order" in the state which, it adds, risks "degenerating into a countrywide religious and ethnic divide, with the potential to spiral into an uncontrollable situation."
The council will give an African force a 12-month mandate to restore order in the former French colony. French troops will have permission to use "all necessary measures" to support the African contingent.
There are about 2,500 troops in the African-led International Support Mission in the Central African Republic (MISCA) that will eventually reach 3,600 and on December 19 become an African Union force.
France has 600 troops there and plans to increase this to 1,200.
But United Nations leader Ban Ki-moon has warned that up to 9,000 troops could be needed if the crisis blows up and a full UN force has to take over.
Violence has worsened in the country of 4.6 million people since the Seleka coalition of rebels forces deposed president Francois Bozize in March.
An interim government led by a former rebel has since lost control. The massacre of 12 Muslim women, children and men this week by suspected Christian radicals highlights the need for "urgent" action, according to French UN envoy Gerard Araud.
"The French forces and the African forces will act as quickly as possible. We need the resolution that will be passed tomorrow, events show how crucial it will be," Araud told AFP on Wednesday.
The Security Council will give MISCA an ambitious mandate for the "stabilization of the country and the restoration of state authority over the whole territory of the country."
But it also calls on Ban to recommend within three months whether a full UN peacekeeping mission should step in.
France has led calls for a UN force to move in but the United States and other Security Council members are more cautious. The resolution calls on the UN to carry out "contingency" planning for the possible transformation into a UN mission.
The resolution orders a one-year embargo on supplying arms and military equipment to the Central African Republic and also orders UN members to stop mercenaries from going there.
It condemns "the escalation of inter-religious and inter-communal violence" and calls for a UN commission of inquiry into killings and mass rapes carried out since March.
The council could order sanctions against individuals behind the strife which UN, US and French officials have warned could turn into genocide.
The UN resolution also warns interim President Michel Djotodia over the lack of progress on a promise to hold national elections by February 2015.
Aid groups have called on the Security Council to send a full peacekeeping force as the crisis grows.
Reacting to the latest spate of bloodshed, the United States expressed shock Wednesday after vigilantes hacked 12 civilians to death.
Christian militiamen attacked Muslim herders late Monday north of Bangui, a military source told AFP, noting that there were children and a disemboweled pregnant woman among the victims.
"The United States is appalled by today's reports of the murder of innocent women and children outside of Bangui," deputy State Department spokeswoman Marie Harf said in a statement.
The International Rescue Committee's chief executive, former British foreign secretary David Miliband, said the "unspeakable cruelty" in the Central African Republic was regularly forcing his group to suspend relief efforts there.
"The lack of attention to (the Central African Republic) has been a green light for abuse," said Miliband, who praised France's intervention.