Britain is to transport foreign troops and equipment to Mali amid efforts to halt an advance by rebels, it has been revealed.
The help was agreed in a phone call between David Cameron and President Francois Hollande, after France sent in forces to support the Malian government.
Downing Street stressed that no UK troops would engage in combat operations in the country, but two transport planes are expected to be deployed within 24-48 hours.
"The Prime Minister spoke to President Hollande this evening to discuss the deteriorating situation in Mali and how the UK can support French military assistance provided to the Malian Government to contain rebel and extremist groups in the north of the country," a spokeswoman said. "The Prime Minister has agreed that the UK will provide logistical military assistance to help transport foreign troops and equipment quickly to Mali.
"We will not be deploying any British personnel in a combat role. They also agreed that the peacekeeping mission from West African countries needs to be strongly supported by countries in the region and deployed as quickly as possible. Both leaders agreed that the situation in Mali poses a real threat to international security given terrorist activity there."
The Government's National Security Council (NSC) is set to discuss the situation in Mali when it meets on Tuesday.
Hundreds of French troops were deployed in Mali on Friday after state forces lost control of a strategically important town to Islamists. The rebels seized a swathe of northern Mali last spring.
President Hollande also sent French commandos into Somalia in a failed attempt to rescue hostage Denis Allex, who was kidnapped in July 2009. Two soldiers and Mr Allex are believed to have died in the bid. Paris insists the two operations are entirely separate. The country's terrorist threat level has been raised over fears of reprisals from extremists.
Earlier, Mr Cameron released a statement expressing "deep concern" about the rebel advances. He said: "I welcome the military assistance France has provided to the Malian government, at their request, to halt this advance.
"These developments show the need to make urgent progress in implementing UN Security Council resolutions on Mali, and ensure that military intervention is reinforced by an inclusive political process leading to elections and a return to full civilian rule. I would also like to send personal condolences to the families of the French hostage killed in Somalia and those of the two soldiers either killed or missing in the rescue attempt."