Sao Tome votes in presidential run-off after incumbent boycotts race

SAO TOME (Reuters) - Voters in Sao Tome and Principe went to the polls on Sunday in the second round of the country's presidential election, with ex-speaker of parliament Evaristo Carvalho guaranteed victory after incumbent Manuel Pinto da Costa boycotted the race. Pinto da Costa quit the run-off in the small island nation in the Gulf of Guinea, alleging irregularities in the first round on July 17, which Carvalho led with 49.88 percent of the vote to Pinto da Costa's 24.83 percent. The former Portuguese colony of some 200,000 people has a semi-presidential system in which the prime minister is the head of government. Pinto da Costa has governed since 2011, after ruling the country as a single-party state from independence in 1975 until 1991. Carvalho finished runner-up in 2011 and is the vice president of Sao Tome's parliamentary ruling ADI party. The country has 19 oil blocks in its exclusive economic zone and an additional joint exploration zone with Nigeria, but it is yet to find any commercially viable oil. (Reporting By Ricardo Neto; Writing by Aaron Ross)