Washington — US military planners have begun to help organise a multinational proxy force to intervene next year in Mali which has become a magnet for Islamist extremists, US officials said Wednesday.

The international force would be led on the ground by several thousand Malian and West African troops but would receive extensive support from the Pentagon and the State Department, which would help train, equip and transport the troops, Obama administration officials said.

The African Union appealed Wednesday for U.N. funding for a military operation to combat Islamist extremists in northern Mali after U.N. chief Ban Ki-moon cautiously recommended the Security Council approve the force without U.N. financing.

Mali descended into chaos in March when soldiers toppled the president, leaving a power vacuum that enabled Tuareg rebels to seize two-thirds of the country. But Islamist extremists, some allied with al Qaeda, have hijacked the revolt.

The AU observer to the United Nations, Antonio Tete, told the 15-member Security Council that the deployment and operations of an African force of 3,300 troops would need "a U.N. support package funded through assessed contributions to ensure sustained and predictable support to the mission."