West African defence chiefs have drawn up a plan for military action if Niger’s coup is not overturned by Sunday, the regional bloc said, after mediation failed in a crisis that threatens regional security and has drawn in global powers.

The Economic Community of West African States (Ecowas) has given Niger’s coup leaders until Sunday to step down and reinstate the elected president, Mohamed Bazoum.

The bloc has taken a hard stance on last week’s takeover, the seventh coup in west and central Africa since 2020.

Given its uranium and oil deposits and pivotal role in the war with Islamist rebels in the Sahel region, Niger has strategic significance for the US, China, Europe and Russia.

The US has paused certain foreign assistance programmes that benefit the government of Niger, but will continue giving humanitarian and food assistance, the US secretary of state, Antony Blinken, said on Friday.

France has said it will support efforts by Ecowas to make the coup fail, but has not not specified whether that would entail military support for an intervention.

The French foreign minister, Catherine Colonna, met the ousted prime minister of Niger, Ouhoumoudou Mahamadou, and the Niger ambassador in Paris on Saturday.

Under the intervention plan, the decision of when and where to strike would be made by heads of states and would not be divulged to the coup plotters, said Abdel-Fatau Musah, the Ecowas commissioner for political affairs, peace and security.

“All the elements that will go into any eventual intervention have been worked out here, including the resources needed, the how and when we are going deploy the force,” he said at the close of a three-day meeting in Nigeria’s capital, Abuja.

Whatever option the 15-nation body chooses, it risks further conflict in one of the poorest regions of the world, where groups linked to Islamic State and al-Qaida thrive on chaos.

It is not clear how much support the bloc has. Neighbouring Chad, which is not part of Ecowas but whose military leader, President Mahamat Idriss Déby, played a role in mediation efforts this week, said it would not intervene militarily.

Chad’s defence minister, Gen Daoud Yaya Brahim, told national television on Friday: “We always advocate dialogue between Nigerians and we will never intervene by military means.”

Ecowas has imposed sanctions on Niger and sent a delegation to its capital, Niamey, on Thursday seeking an “amicable resolution”. But a source in the entourage said they were rebuffed and did not stay long.

“We want diplomacy to work, and we want this message clearly transmitted to them that we are giving them every opportunity to reverse what they have done,” Musah said.

The Nigerian president, Bola Tinubu, told his government to prepare for options including deployment of military personnel, in a letter read out to the country’s senate on Friday. Senegal has also said it would send troops.