Prime Minister of Sao Tome and Principe Maria das Neves resigned on Friday, Portugal's Lusa news agency reported.
Sources in the prime minister's office was quoted as saying that Das Neves, who has been prime minister of the archipelago since September 2002, resigned because of the political crisis facing the island state since the abortive coup.
Das Neves was one of the ministers who was held by the putschists at a military camp following the military takeover on the island country.
President Fradique de Menezes was deposed in a bloodless coup by military officers on July 16.
He was allowed to return to office on July 23 following a dealwith the leaders of the takeover which provides for the creation of a new government of national unity as well as an amnesty for the putschists.