Burkinabe President Blaise Compaore, who had taken the lead in efforts to mediate a peaceful solution to the crisis, has given instructions for the deployment as part of the international support mission in Mali, Foreign Minister Djibrill Bassole told reporters.

"A contingent of 500 men from the Burkinabe armed forces will take part in the deployment to help the Malian army defend territorial integrity," Bassole said.

The announcement came after France sent its air force to back Malian troops, pinning back the Islamists as they threatened to advance from their northern strongholds southward on the capital Bamako.

The United Nations Security Council has approved the deployment of a 3,300-strong military mission by regional bloc ECOWAS (Economic Community of West African States) but officials have said a deployment was unlikely before September.