Ten people were killed in Nigeria during protests marking the anniversary of the country's civil war, according to the police, but campaigners said the death toll was much higher.
Activists wanting a separate state for the Igbo people in the southeast were commemorating the 49th anniversary of the declaration of an independent Republic of Biafra on May 30, 1967.
Police said officers opened fire on Monday because members of the Indigenous People of Biafra (IPOB) movement shot at security forces deployed to monitor the rallies - a claim denied by the group.
"We had to deploy our officers to ensure that the protest was peaceful but we were surprised that the people turned violent," Delta police spokesman Charles Muka told the AFP news agency on Tuesday.
The police spokesman also said "five corpses were recovered" in Onitsha, while in the capital of neighbouring Delta state, Asaba, the police said five protesters were killed.
There was also violence in the capitals of Imo, Ebonyi, Abia and Rivers state, he added.
But IPOB spokesman Anayo Chukwu-Okpara denied that the group's members had attacked police, and said at least 35 members of the group were killed in the commercial hub of Onitsha in Anambra state.
Al Jazeera's Yvonne Ndege, reporting from the capital, Abuja, said: "The background to all of this stems from decades of unhappiness and dissatisfaction since the civil war happened.
"People in that part of the country were never satisfied with what they got from the state," she added.
The civil war lasted until January 1970 and left more than one million people dead, many of them from starvation and disease.
Source: Al Jazeera And AFP