(AFP) - West African leaders met in Nigeria's capital Abuja on Sunday for talks on their region in deepening crisis, after four countries fell under military rule and with risks growing from Sahel jihadist conflicts.

After coups in Mali, Burkina Faso, Guinea and Niger since 2020, the Economic Community of West African States or ECOWAS saw member states Sierra Leone and Guinea-Bissau report attempted coups in recent weeks.

A French military withdrawal from the Sahel -- the region along the Sahara desert across Africa -- has heightened concerns over conflicts spreading southward to Gulf of Guinea states Ghana, Togo, Benin and Ivory Coast.

International attention has focussed on the most recent coup in Niger in July after troops ousted President Mohamed Bazoum, prompting ECOWAS to impose tough sanctions and close trade.

Niger -- a key Western partner in the fight against Sahel militants -- has demanded French troops based there leave, while the US still has military personnel in the country.

But recent talks with the regime in Niamey stalled. ECOWAS called for Bazoum's immediate return to power, but Niger's rulers have kept the ousted president in detention and want up to three years for a transition back to civilian rule.

"The military authorities have unfortunately shown little remorse as they hold on to their untenable positions, holding not only President Bazoum, his family, and members of his government hostage, but also the people of Niger," ECOWAS commission president Omar Touray told the summit opening.

Touray said ECOWAS recognised the "dire humanitarian" situation in Niger, but accused the rulers in Niamey of interfering with the flow of aid that was allowed into the country.

In a possible signal of ECOWAS maintaining its hardline on Niamey, exiled Niger Prime Minister Ouhoumoudou Mahamadou attended the Abuja summit.

Nigeria's President Bola Ahmed Tinubu is current chair of ECOWAS and US Assistant Secretary of State for African Affairs Molly Phee was also at the meeting to discuss how to support Niger's return to democratic rule and Sahel security.

The ordinary summit will also discuss delayed or uncertain transitions back to civilian rule and elections for Mali, Burkina Faso, Guinea and Niger.

Tinubu called for the "re-engaging with the countries under military rule on the basis of realistic and short transition plans".

- Mediator -

Earlier this month, Nigeria said it was asking the Niger regime to free Bazoum and allow him to fly to a third country, as a step to opening talks on lifting sanctions.

But Niger's military leaders rejected that option and have asked Togo's President Faure Gnassingbe to act as a mediator.

Before Sunday's ECOWAS meeting, Niger's military leader General Abdourahamane Tiani and some of his ministers visited Togo on Friday to strengthen bilateral ties.

"Tiani is willing to talk over the length of the transition and over the situation with Bazoum," said a Togolese diplomatic source.

ECOWAS has also left on the table the last option of a military intervention in Niger though analysts say that appears increasingly unlikely.

Since French troops began leaving the region, military regimes in Niger, Mali and Burkina -- struggling with jihadist violence -- have hardened their positions and joined forces in an "Alliance of Sahel States".

"This phantom, push back-alliance appears intended to divert attention from our mutual quest for democracy and good governance," Tinubu told the summit.

Last month, armed attackers stormed military posts, prisons and police stations in another ECOWAS member Sierra Leone, in what the government called a coup attempt that killed 21 people.

A week later Guinea-Bissau also denounced an attempted coup, with fighting between the national guard and special forces of the presidential guard.

© Agence France-Presse