The ECOWAS said it “firmly condemned” the latest developments in the country, which it was “following with great concern”.
Those developments include the “successive investiture of two heads of state outside of legal and constitutional frameworks and the co-existence of two Prime Ministers,” ECOWAS said in a statement.
Since Friday, the army has moved into several institutions, including ministries and the national assembly, and took control of local radio and television stations.
While ex-prime minister and military general Umaro Sissoco Embalo was declared winner of the presidential election by the electoral commission, the ruling party rejected the results and challenged them in the Supreme Court.
Last week, Embalo swore himself in as president, while the African Party for the Independence of Guinea and Cape Verde (PAIGC), which enjoys a majority in parliament, also installed a rival president and prime minister.
According to Guinea’s National Electoral Commission (CNE), 47-year-old Embalo polled 54% of the vote versus 46% for the ruling party candidate Pereira.
The next president of the country faces an uphill task to combat widespread poverty and an unstable political system in which the majority party appoints the government but the president can dismiss it.
Traffickers also exploit Guinea-Bissau’s unpoliced waters and maze of picturesque forested islands to ship South American cocaine destined for Europe.