The Economic Community of West African States (ECOWAS) on Tuesday condemned what it calls an "attempted coup" in Guinea-Bissau and called on the military to "return to their barracks".
It follows reports of men in civilian clothing opening fire close to a government building hosting a meeting between the president and prime minister of Guinea-Bissau, whose whereabouts remain unknown.
"Ecowas is following with great concern the evolution of the situation in Guinea-Bissau... where military gunfire is taking place around the government palace," Reuters quotes the statement as saying.
"Ecowas condemns this attempted coup and holds the military responsible for the safety of President Umaro Sissoco Embaló and members of his government."
Last week Ecowas suspended another of its members, Burkina Faso, which is also facing uncertainties due to a military coup on January 24.