Downing Street says military assistance is being provided to stop terrorists establishing a haven on 'Europe's doorstep'. -----SKY NEWS
Britain will provide transport planes to assist the French military operation in Mali, Downing Street has confirmed.
French military strikes on the country have already claimed the lives of at least 100 rebels in a fight over the strategic town of Konna.
Mr Hollande has raised his country's terror threat level amid fears of retaliatory terror attacks in France.
He said that France "has to take all necessary precautions" in the face of a terrorist threat, including "surveillance of our public buildings and our transport network."
A Downing Street spokesman said: "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.
"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.
"Both leaders agreed that the situation in Mali poses a real threat to international security given terrorist activity there.
"They discussed the need to work with the Malian Government, regional neighbours and international partners to prevent a new terrorist haven developing on Europe's doorstep and to reinvigorate the UN led political process once the rebel advance has been halted.
"The National Security Council, which was already due to meet on Tuesday, will now consider the situation in Mali and and discuss what needs to be done to secure a lasting political settlement in Mali."
One French pilot has been killed in the military action and hundreds of French soldiers have been deployed in the West African country.
Mr Hollande took action in Mali at the request of interim President Dioncounda Traore, who has declared a state of emergency.
Western governments expressed alarm on Thursday after an al Qaeda-linked rebel alliance captured Konna, a gateway towards the capital Bamako 600km (375 miles) south.
The Malian army has said it was attacking the "last pockets of resistance" by insurgents in Konna after they recaptured it with the help of the French.
Mr Hollande said the "terrorist groups, drug traffickers and extremists" in northern Mali "show a brutality that threatens us all." He vowed that the operation would last "as long as necessary".
The West African regional bloc ECOWAS has now authorised the immediate deployment of troops to Mali.
The bloc's commission president Kadre Desire Ouedraogo said it made the decision "in light of the urgency of the situation".
For the past nine months, the Islamic militants have controlled a large swathe of northern Mali, a lawless desert region where kidnapping has flourished.
Mr Hollande said the operation was aimed in part at protecting 6,000 French citizens in Mali, including seven who are being held captive.
UN Secretary-General Ban Ki-moon said Senegal and Nigeria also responded to an appeal from Mali's president for help to counter the militants.
Late last year, the 15 nations in West Africa, including Mali, agreed on a proposal for the military to take back the north, and sought backing from the UN.
The Security Council authorised the intervention but imposed certain conditions, including the training of Mali's military, which has been accused of serious human rights abuses since a military coup last year sent the nation into disarray.
Al Qaeda's affiliate in Africa has been a shadowy presence for years in the forests and deserts of poverty-stricken Mali.
Most Malians adhere to a moderate form of Islam, but in recent months the terrorist group and its allies have taken advantage of political instability, taking territory they use to stock weapons and train forces.
The Islamists have insisted they want to impose Sharia only in northern Mali, though there long have been fears they could push further south.