Former Sao Tome and Principe leader Manuel Pinto da Costa will return to power after winning a presidential run-off in the African island nation.

The country's election commission said Monday that Mr. Pinto da Costa defeated Parliament Speaker Evaristo de Carvalho in Sunday's voting, 53 to 47 percent.

Mr. Pinto da Costa had won the first round of voting and earned the backing of most of the eliminated candidates.

His election has raised concerns that Sao Tome may slide back into the authoritarian rule seen during Mr. Pinto da Costa's first term. The former and future president, who is 74, led a one-party socialist state from 1975 to 1990.

He is due to take office next month, succeeding President Fradrique de Menezes, who was constitutionally barred from seeking a third term.

Mr. Pinto da Costa has said he will make improving the economy and fighting corruption his top priorities.

Sao Tome is a former Portuguese colony that won independence in 1975.

Since then, it has suffered chronic poverty and periodic instability highlighted by failed coup attempts in 1995 and 2003. The two-island nation, located in the Gulf of Guinea, is believed to have significant oil reserves and the potential for a tourism industry.