A small number of UK special forces soldiers are already on the ground in Mali helping to co-ordinate and advise the French military effort against the jihadi groups in the north.

They are part of a team of British military and MI6 personnel in the country who are providing support to French commanders. None of the special forces soldiers are being deployed in a combat role, sources insisted.

The UK is also preparing to answer a call from the French for extra help with reconnaissance aircraft, which is expected to include RAF Sentinels, which were used during the Libya campaign.

The planes have high-resolution radars and GMTI (ground moving target indicators), which would help French strike aircraft to find and attack enemy positions.

Imagery from UK military satellites will also be offered to the French.

The two C-17 transport aircraft already used to help French troops and equipment into Mali are also available for continued use, if needed.

The UK had considered making available some of the military's small, tactical drone aircraft, which can be used to scope battlefields, but it is understood the equipment, and the teams operating them, are all needed in Afghanistan.

"The prime minister has made it clear that the help the UK will provide is of the intelligence and logistical variety," said a Whitehall source, who did not want to be named. Even if the French asked for more help from UK special forces, this would prove difficult, because so many units are deployed in Afghanistan.

"The prime minister has been pretty explicit about what help we can provide, and he has said we will not be deploying combat troops," the source added.

A meeting of the national security council, chaired by David Cameron, went through the various options, and the Ministry of Defence and Foreign Office will now liaise with the French to refine what they need, and what can be given.

The UN secretary general, Ban Ki-moon, said on Tuesday "dialogue is not possible at this time" with Mali's Islamic insurgents and applauded France's military intervention, which he described as a "courageous decision". Ban added that the solution to the country's ongoing unrest would depend on political, diplomatic and military means.

The Nigerian president, Goodluck Jonathan, said on Tuesday his troops would stay in northern Mali until the crisis there was resolved and a democratically elected government in place.

"We cannot pull out until we have solved the problem. I cannot tell you when we will solve the problem, but Nigeria is totally committed and we remain committed until the crisis is resolved," he told Reuters in Geneva.