Yenagoa - Nigeria's ruling party candidate has been elected governor of President Goodluck Jonathan's home state, election officials said on Sunday, ending months of political uncertainty over who is in charge of the oil-producing state.

The People's Democratic Party (PDP) candidate Henry Dickson won more than 90 percent of votes in Bayelsa state, the Independent National Electoral Commission said, further strengthening the PDP's stranglehold on power there since Jonathan became president.

Some opposition parties refused to accept the result, saying there were irregularities, including ballot box snatching, multiple voting and harassment of party officials.

The race had been particularly contentious after the PDP stopped the last governor, Timipre Sylva, competing for the party candidacy last November - the first time it had taken such a step - provoking Sylva to challenge the decision through the courts.

Nigeria's 36 state governors control huge budgets and are some of the most powerful politicians in the country. Western diplomats said Sylva was snubbed because he fell out with his former ally Jonathan.

At least one person was killed and several injured at a pre-election rally on Tuesday in the southern Ijaw region in Bayelsa, witnesses said. Turnout during Saturday's ballot was low due to security concerns, election officials said.

Elections have frequently turned violent and 15 000 police were deployed in Bayelsa on Saturday to deter any potential unrest. Around 800 people were killed after last year's presidential election in three days of violence between rival supporters and in clashes between Christian and Muslim gangs.

That vote was hailed by international observers and many Nigerians as the fairest since the end of military rule in 1999.

Bayelsa is one of the three Nigerian states that make up the oil-producing Niger Delta, where, for several years, militant gangs blew up pipelines, stole tankerloads worth of oil and kidnapped foreign oil workers, until an amnesty in 2009.

Attacks on oil installations in the delta have been rarer and less destructive since the 2009 amnesty but they still occur.

Last week the Movement for the Emancipation of the Niger Delta (MEND), formerly Nigeria's main militant threat, claimed a strike on a pipeline in Bayelsa owned by Italian firm Eni , which confirmed 4 000 barrels per day of output had been cut by the attack.

The government said the attack was carried out by other criminals posing as members of MEND. - Reuters