In recent days, members of the Indigenous People of Biafra (IPOB) movement have clashed with security services in the southern city of Port Harcourt and southeastern state of Abia.
The military claims a build-up of troops in Abia around the home of IPOB leader, Nnamdi Kanu, in the state capital, Umuahia, is part of an operation against violent crime.
But IPOB suspects it is designed to crack down on its activities. The group wants an independent state for the Igbo people who dominate the southeast.
Clashes risked taking on a wider ethnic dimension after youths from the Hausa ethnic group dominant in the north attacked Igbo market traders in the central city of Jos.
Amnesty International, which has alleged military abuses against IPOB protesters in the past, called for calm and restraint on all sides in response to the southeast unrest.
Defence spokesman Major General John Enenche meanwhile rejected claims from IPOB that it is non-violent, saying it had been “terrorising the general public”.
The group had formed its own intelligence service and national guard, blocked public roads and extorted money at illegal checkpoints, he said in an emailed statement.
Stones, Molotov cocktails and broken bottles were used against troops, he said, adding that IPOB “from all intent, plan and purpose… is a militant terrorist organisation”.
– ‘Avoidable and unnecessary’ –
Nigeria, which is almost evenly split between a predominantly Muslim north and largely Christian south, is a country of barely concealed religious and ethnic tensions.
Violence frequently erupts but Biafra is a particularly sensitive issue as a previous unilateral declaration of independence in 1967 sparked a brutal, 30-month civil war.
More than one million people were killed, most of them Igbos.
In Jos, the capital of the central state of Plateau, governor Simon Lalong summoned Hausa and Igbo community leaders for talks following skirmishes on Thursday.
At least two people were reported to have been killed in violence at two markets but police managed to restore control by firing warning shots into the air, eye-witnesses said.
The Hausa youths reportedly accused the Igbos of “killing Hausas in the southeast”, although there has been no official confirmation of such claims.
Lalong, who called the clashes “avoidable and totally unnecessary”, imposed an indefinite dusk-to-dawn curfew in the city on Thursday.
Jos and rural Plateau state has been hit repeatedly in the past by deadly religious, sectarian and ethnic violence.
In June, Igbo people living in the northern city of Kaduna were told to leave, as separatist sentiment surged in different parts of the country.
Kaduna neighbours Plateau state to the west.
In the northwestern state of Niger, governor Abubakar Sani Bello warned citizens against “hate speeches, violent agitation, rumour and sentiment” as well as reprisal attacks.
“Niger state is very central in Nigeria’s evolution and has always been a melting pot of people from various parts of the world,” he said in a statement.
– Curfew extended –
A Nigerian army spokesman, Colonel Sagir Musa, rejected as “baseless and mischievous” claims that troops invaded Kanu’s compound in Umuahia.
Kanu is currently on bail pending the resumption of his trial in the capital, Abuja, on charges of treasonable felony.
An AFP correspondent in Abia’s commercial hub, Aba, said police were assessing damaged property, including gutted shops and vehicles.
Security had been increased around Hausa community mosques and at strategic points in the city.
The atmosphere was generally calm, he said, but state governor Okezie Ikpeazu extended an overnight curfew until Sunday.
He also ordered state schools to postpone the start of term from Monday until September 25 “to ensure the safety of our children”.
“It is our hope that all the measures taken so far will help to rapidly restore full normalcy to all areas of the state,” he added.