The military commander who has ruled Guinea since a coup four years ago has entered the presidential race, breaking an earlier promise to hand power to a civilian government.

Col Mamadi Doumbouya submitted his candidacy at the Supreme Court on Monday, flanked by soldiers and wearing black sunglasses. He did not make any public comment.

Two of Guinea's biggest opposition parties - RPG Arc en Ciel and UFDG - have been excluded from December's contest, raising concerns about the election's credibility.

Guineans reacted with shock last month when it was announced that presidential candidates would need to pay a deposit of 875m Guinean francs ($100,000; £75,000) to contest the election.

While the previous deposit was almost as high - 800m francs - some analysts had hoped it would be reduced to encourage more people to stand.

Four years ago, Col Doumbouya had pledged to hand power back to civilians, stating, Neither I nor any member of this transition will be a candidate for anything... As soldiers, we value our word very much.

The election is being held under a new constitution that allows Col Doumbouya to run for the presidency. Under his rule, the Guinean authorities have been cracking down on peaceful dissent, restricting internet access, and brutally suppressing demonstrations.

Col Doumbouya justified deposing then-President Alpha Condé on similar charges, including rampant corruption and human rights abuses. Now aged 40, he is the youngest head of state in Africa.

December's election will unfold without several prominent figures, as former President Alpha Condé and some ex-Prime Ministers are currently living abroad.