A powerful bloc of west African states has suspended ties with Niger after a coup there and authorised the possible use of force if the country’s democratically elected president, Mohamed Bazoum, is not released and reinstated within a week. The ultimatum was delivered by the Economic Community of West African States (Ecowas) as France warned that any attacks on French citizens or its interests in Niger – a former colony – would provoke an “immediate and stringent” reaction. France’s embassy in Niamey, Niger’s capital, was targeted during pro-junta and pro-Russia protests on Sunday. Thousands of protesters marched through the streets of the city waving Russian flags, chanting the name of Vladimir Putin and forcefully denouncing France. According to a witness at the French embassy and videos seen by the Associated Press, a crowd congregated outside the building and a door was set on fire. Reports suggested French flags were burned at the embassy, leading police to fire teargas at protesters. Images seen by Reuters showed the embassy walls on fire and people with bloodied legs being loaded into ambulances. Black smoke rose across the city as the Nigerien army broke up the crowd of demonstrators. Ecowas, which met in Nigeria to discuss the crisis on Sunday, also threatened to suspend all commercial and financial transactions between Niger and the organisation’s 15 member states, and to freeze the country’s assets in the bloc’s central banks. Ecowas and the eight-member West African Economic and Monetary Union are focused on finding ways to restore Bazoum, who was deposed by Gen Abdourahamane Tchiani, the head of Niger’s presidential guard. Tchiani, who led the coup on Wednesday, was declared head of state two days later. Last year Ecowas agreed to create a regional security force to intervene against jihadists and prevent military coups, but details of the proposal remain unclear. The bloc said: “In the event the authorities’ demands are not met within one week, [we will] take all measures necessary to restore constitutional order in the republic of Niger. Such measures may include the use of force. To this effect, the chiefs of defence staff of Ecowas are to meet immediately.” Niger’s new military junta has already said it is prepared to respond to any possible military intervention. Col Amadou Abdramane, a spokesperson for the junta, said in a statement read out on state TV on Saturday night: “The objective of the [Ecowas] meeting is to approve a plan of aggression against Niger through an imminent military intervention in Niamey in collaboration with other African countries that are non-members of Ecowas and certain western countries. We want to once more remind Ecowas, or any other adventurer, of our firm determination to defend our homeland.” The junta issued a second statement on Saturday night urging citizens in the capital to take to the streets from 7am local time to protest against Ecowas and show support for the new military leaders. Mahamat Idriss Déby, the president of Chad, volunteered to travel to Niger to speak to the coup leaders and report back to the Nigerian president, Bola Tinubu, who is the chair of Ecowas, the Reuters news agency reported, citing two sources in the Nigerian presidency. The coup in Niger has been widely condemned by neighbouring countries and international partners, which have refused to recognise the new leadership and demanded that Bazoum be restored to power. Bazoum has not been heard from since early on Thursday, when he was confined within the presidential palace, although the EU, France and others have said they still recognise him as the legitimate president, and he has been able to speak to some international leaders. The mutineers said they overthrew Bazoum, who was elected two years ago in Niger’s first peaceful, democratic transfer of power since independence from France, because he was unable to protect the nation from growing jihadist violence. But some analysts and Nigeriens say the claim has served as a pretext for a takeover that is more about internal power struggles than securing the nation. Amad Hassane Boubacar, a professor at Abdou Moumouni University of Niamey, said: “Everybody is wondering: why this coup? That’s because no one was expecting it. We couldn’t expect a coup in Niger because there’s no social, political or security situation that would justify that the military take the power.” While Niger’s security situation is dire, it is not as precarious as that of neighbouring Burkina Faso or Mali, which have also been battling an insurgency linked to al-Qaida and Islamic State. Last year, Niger was the only one of the three in which violence declined, according to the Armed Conflict Location & Event Data Project. Until now, Niger had been seen as the last remaining reliable partner for the west in efforts to battle jihadists in the Sahel region of Africa, where Russia and western countries have vied for influence in the fight against extremism. France has 1,500 soldiers in the country who conduct joint operations with the Nigeriens, while the US and other European countries have helped train the nation’s troops. Although the Russian mercenary group Wagner is operating in Mali, and Putin would like to expand Russia’s influence in the region, it remains unclear whether the junta leaders are planning to move towards Moscow or stick with Niger’s western partners. Conflict experts say Niger is the regional power with the most to lose if it turns away from the west and the millions of dollars of military assistance the international community has provided. On Saturday, the US secretary of state, Antony Blinken, said the continued security and economic arrangements that Niger had with the US hinged on the release of Bazoum and “the immediate restoration of the democratic order in Niger”. On Saturday, France suspended all development aid and other financial assistance for Niger and called for an immediate return to constitutional order.