A former leader of the African nation Sao Tome and Principe will face the country's parliament speaker in a runoff election, after neither captured a majority in Sunday's presidential vote.

The country's election commission said Monday former president Manuel Pinto da Costa led Sunday's voting with 35 percent. He led a one-party socialist state from 1975 until 1990.

Evaristo de Carvalho, who is the parliament speaker and a former prime minister, captured 21 percent of the vote.

In all, 10 candidates competed to succeed President Fradique de Menezes, who is constitutionally barred from seeking a third term.

The tiny archipelago, located in the Gulf of Guinea, is believed to have significant oil reserves and the potential for a thriving tourism industry.