At least 13 people have been killed in attacks by gunmen on two police stations and a hotel in the Nigerian oil city of Port Harcourt.
Four police officers and six attackers died along with three civilians who were hit by stray bullets in an attack on one of the police stations.
Several other people are reported to have been killed in an attack on a night club in the city.
Niger Delta militants have reportedly said they carried out the attacks.
The Niger Delta Vigilante Movement, led by Ateke Tom, is demanding the return of rice and cattle seized during a recent raid in their base by the authorities.
Government planes also bombed suspected training camps thought to be run by the group in mangrove swamps and creeks south of the city.
The military acted after peace talks between the group and the government broke down.
Militants in the region are demanding greater control over local oil reserves, which are vital to Nigeria's economy.