An overnight curfew was imposed in Nigeria's southern Rivers state as tensions ran high over local results of the country's general election, the state government said on Monday.
"The government has imposed a curfew in Rivers state from 7:00 pm (1800 GMT) to 6:00 am to prevent the breakdown of law and order because of the tense political situation," said information commissioner Ibim Semenitari.
Rivers, in the oil-producing Delta region, is a key battleground in the election, which is seen as the closest in Nigeria's history.
The main national opposition All Progressives Congress (APC) has held protests in the state capital Port Harcourt, accusing the ruling Peoples Democratic Party (PDP) of widespread vote-rigging.
Thousands of supporters took to the streets on Sunday and Monday, calling for the election to be re-run in the state, which is next door to President Goodluck Jonathan's home in Bayelsa.
The APC controls Rivers after governor Rotimi Amaechi defected from the PDP in 2013 and he has since become a top critic of the government.
On Monday, female supporters of the APC were teargassed as they tried to converge on the offices of the local electoral commission.