West African nations will seek a U.N. Security Council mandate for military intervention in Mali where rising Islamist militancy has made the country an international security threat, Niger's President Mahamadou Issoufou said on Monday.

"ECOWAS (Economic Community Of West African States) has decided to refer to the Security Council with the objective of sending an armed force to Mali," Issoufou told a news conference after meeting French President Francois Hollande in Paris.

"I asked for the support of France for the resolution we are preparing," he said.

Mali, once regarded as a good example of African democracy, collapsed into chaos after soldiers toppled the president in March, leaving a power vacuum that enabled Tuareg rebels in the north to take control of nearly two-thirds of the country.

The uprising also involved a mix of local and foreign Islamists, and Western diplomats talk of the risk the region could turn into a "West African Afghanistan".

Issoufou said Afghan and Pakistani Islamist groups were training recruits in northern Mali.

"It is not just a threat for the region, but the world ... It is an international threat that needs an international response so this is why we have decided to take this to the Security Council," he said.

Issoufou said ECOWAS, which is still preparing its Security Council request, would seek logistical support from the United States and France for any military intervention.

The bloc wants a "Chapter 7" mandate if talks with armed groups fail to resolve the escalating crisis, he said. Chapter 7 of the U.N. charter allows the Security Council to authorise actions ranging from sanctions to military interventions.

ECOWAS has said for weeks it has troops ready but the cost of such a mission - which peacekeeping sources estimate at more than $200 million - and confusion over its objectives mean any deployment is probably still far off.

Former colonial ruler France, which has six of its citizens held hostage in un unknown location in the region by al Qaeda's north African arm (AQIM), has said it would be ready to help restore stability in Mali if there is a Security Council resolution.

Hollande said Paris would be ready to support military action as "there is a threat of terrorist groups taking root in northern Mali," but, he said, it was up to African nations to take the initiative in leading any military operation.