At least 100 members of the Biafran Zionist Movement, a separatist group, have been arrested in south-eastern Nigeria.
They were arrested after declaring independence, raising the Biafran flag and then marched through the region's main town, Enugu.
More than one million people died during the 1967-70 Biafran conflict - mostly from hunger and disease.
Most of those arrested were young men, but some were veterans of the war. All were remanded in custody.
The BBC reports they gathered on Sunday to mark the birthday of former Biafran leader Chukwuemeka Ojukwu, who died in November 2011 and was buried in March.