ONITSHA, Nigeria June 21 (Reuters) - Large crowds of voters gathered in Nigeria's southwest Ekiti state on Saturday for a hotly contested local election that will be scrutinised for fairness and signs of violence ahead of next year's national poll.
The election for state governor - a powerful position in Africa's biggest economy - will also be a barometer for President Goodluck Jonathan's ruling People's Democratic Party (PDP), which in 2015 is likely to see its sternest test since sweeping to power after the end of military rule in 1998.
People started queuing up hours before the formal start of voting at noon (1200 GMT), officials said.
"No adverse reports have been received from across the state. There are rumours here and there which we are checking," said Ikechukwu Aduba, the official in charge of operations for the election.
The United States will be watching the vote with "great interest," Washington's ambassador to Nigeria, James Entwistle, said in a statement. A free and peaceful election would help demonstrate the credibility of the electoral system, he said.
Governors are among the most powerful figures in Africa's largest oil producer. Some control budgets bigger than those of many African countries and their influence carries a great deal of weight in selecting presidential candidates.
In one early sign of tension, officials said the opposition governor of the southern Rivers state was detained by security forces on Thursday on his way into Ekiti for a party rally. The authorities were not available for comment.
The main opposition All Progressives Congress (APC) was created out of four regional parties last year - presenting a nationwide challenge to the ruling movement.
Past, smaller, attempts at opposition alliances have fallen apart. But the APC has been emboldened by the defection of several governors from the ruling party last year.
It has also launched broadsides at Jonathan's handling of the abduction of 200 girls from a school in northeast Nigeria by Islamist militants in April.
The election pits the incumbent Kayode Fayemi, a member of the APC, against former governor Ayo Fayose of the PDP. Opeyemi Bamidele, a Labour Party lawmaker, is also running.
More than 800 people were killed and 65,000 displaced in three days of violence following the 2011 presidential election, Human Rights Watch has said. Rioting erupted mainly in the mostly Muslim north after Jonathan, a Christian from the south, won the vote. (Reporting by Anamesere Igboeroteonwo; writing by David Dolan; editing by Andrew Heavens)