West African leaders meet at an emergency summit Sunday to firm up military plans to win back Islamist-held northern Mali, as fears grow over the risks the extremists pose to the region and beyond.

Leaders from the 15-nation Economic Community of West African States will meet in the Nigerian capital Abuja to approve a military blueprint for action. That plan will eventually be sent via the African Union to the UN Security Council for review.

Countries from outside ECOWAS have also been invited to attend the summit, including South Africa, Mauritania, Morocco, Libya, Algeria and Chad, according to a source from the bloc.

Discussions so far have involved the deployment of more than 3,000 troops from the region, backed by soldiers other countries. The ECOWAS source said military chiefs were requesting a total of 5,500 troops.

Regional leaders have stressed that dialogue remains the preferred option to resolve the crisis in Mali's north, but they have also warned that talks are not open-ended.

ECOWAS Commission President Kadre Desire Ouedraogo has said that the bloc should pursue a dual approach of dialogue and military pressure.

The UN special envoy for the Sahel, Romano Prodi, a former prime minister of Italy and ex-president of the European Commission, has said every effort would be made to avoid military intervention.

But some analysts have questioned whether a negotiated solution is possible with Islamist extremists intent on establishing a theocratic state.

"There's a sense in which (military force) is the only course open, because clearly there's nothing to negotiate," said Jibrin Ibrahim, head of the Nigeria-based Centre for Democracy and Development.

At the same time, analysts and others warn of the risks a continued occupation of the north poses to countries beyond Mali. They say it could provide a safe haven to Al Qaeda-linked extremists and criminal groups.

The ECOWAS military strategy the leaders are to examine Sunday was drawn up with the help of experts from the European Union, African Union, UN and the region. The region is also seeking logistical support from elsewhere.

Foreign and defence ministers from five European countries -- France, Germany, Italy, Poland and Spain -- are expected to meet next Thursday to discuss a European mission train Malian troops.

Algeria, seen as important to any military operation, has been hesitant to get involved, preferring a negotiated solution.

While not a member of ECOWAS, Algeria is viewed as key due to its superior military capabilities, intelligence services and experience battling Islamist extremism. It also shares a 1,400-kilometre (875-mile) border with Mali.

Mali rapidly imploded after a coup in March allowed Tuareg desert nomads, who had relaunched a decades-old rebellion for independence, to seize the main towns in the north with the help of Islamist allies.

The secular separatists were quickly sidelined by the Islamists, who had little interest in their aspirations for an independent homeland and set about implementing their version of strict sharia law.