Guinea-Bissau's new prime minister resigned on Friday following international pressure over President Jose Mario Vaz's controversial sacking of the earlier government just weeks before elections.
The European Union, the African Union and the ECOWAS West African regional bloc have criticised Vaz's move that triggered a political standoff ahead of planned presidential elections in November.
Vaz tried to end months of confrontation between him and the government by firing prime minister Aristides Gomes and his whole cabinet in October, but Gomes refused to step down.
Faustino Imbali, named premier 11 days ago, handed over his resignation letter at the presidential palace, state secretary and Imbali spokesperson Francelino Cunha told AFP.
"We are waiting for the response of the president," Cunha said.
ECOWAS on Wednesday gave Guinea-Bissau's "illegal government" a 48-hour ultimatum to resign or face sanctions.
The UN Security Council had also called on the authorities to respect the November 24 election date and rejected Vaz's appointment of a new government.
Vaz, 61, has governed since 2014 in Guinea Bissau, a state struggling with poverty, corruption and drug trafficking.
Home to fewer than 2 million people, it has seen a series of coups since independence from Portugal in 1974, as well as an 11-year civil war.