Authorities in Nigeria say scores of people are missing, following clashes between supporters of President Olusegun Obasanjo's party and a rival political group.
Police in Nigeria's southeastern Rivers state said the clashes began Saturday, as supporters of President Obasanjo's People's Democratic Party and the main opposition All Nigeria People's Party rallied in the town of Bakana.
The town lies in a swampy area near the oil producing city of Port Harcourt. Witnesses said scores of people fell into a waterway as they ran to escape the fighting.
State police said the clashes were the result of a land dispute and were not political in nature.
Political leaders in Nigeria said they are concerned the fighting could destabilize the country before general elections scheduled for April 12, and presidential elections that are due to take place April 19.
Politicians who are part of an influential group in the north of the country, a bastion of the opposition, wrote a letter to President Obasanjo saying they fear the violence may cause the postponement of the elections.
Nigeria, the world's sixth largest oil producer, is reeling from ethnic clashes earlier this month that forced foreign oil companies to halt operations. The shutdowns have cut total daily oil production by 40 percent.
President Obasanjo, whose election in 1999 returned Nigeria to civilian rule following a long series of military governments, is due to face more than a dozen challengers on April 19. He has called for peace in the days leading up to the elections.
Analysts say the poll will be an important test of the strength of democracy in Africa's most populous nation.