In a stark warning, Buhari said that the country will remain united despite incessant demands from some parts of Nigeria that want independence. "Nigeria's unity is settled and not negotiable. We shall not allow irresponsible elements to start trouble and when things get bad they run away and saddle others with the responsibility of bringing back order, if necessary with their blood. Every Nigerian has the right to live and pursue his business anywhere in Nigeria without let or hindrance," Buhari said.

Buhari also did not mince words about the videos that have been circulating on different social media platforms. "I was distressed to notice that some of the comments, especially in the social media have crossed our national red lines by daring to question our collective existence as a nation. This is a step too far."

In the meantime, the whereabouts of Biafran leader Nnamdi Kanu remain unknown amid renewed protests and a military operation in southeast Nigeria. State governors have urged calm.

Nigerian governors on Friday called for calm after renewed protests by pro-Biafra supporters calling for independence. The Indigenous People of Biafra (IPOB) group led by Nnamdi Kanu wants to break away from Nigeria and create a separate state for the predominantly Igbo people in southeastern Nigeria.

Windscreens of police vehicles have been smashed, petrol bombs thrown, bonfires lit on streets to restrict movement and warning shots fired, in the latest violence. Simon Lalong, governor of Plateau State in central Nigeria, convened a meeting of leaders from the Hausa and Igbo communities following violence at two markets. Two people were reportedly killed and calm was only restored after police fired warning shots in the air.

The violence has also claimed the lives of two police officers. More than 30 Biafra supporters have been arrested, the Daily Post, a local online daily reported. Shops belonging to ethnic Hausas have been attacked by pro-Biafra agitators in Aba and Port Harcourt, according to local media.

Read more: Is Nigeria's one nation policy at stake?

Read more: Biafra: Dreaming of a new state

"There are very conflicting reports of violence on both sides," Isa Sanusi, spokesperson for Amnesty International in Nigeria, told DW in an interview. "There are reports of violence on the side of the military and there are reports of violence on the side of supporters of the Biafra movement."

Where is Nnamdi Kanu?

Nnamdi Kanu's whereabouts are unknown following an invasion of his home by the military, two local newspapers, the Premium Times and Naija News reported. Ifeanyi Ijeafor, a lawyer representing Nnamdi Kanu told DW, the army had gone to his client's home with the intention of assassinating him.

"I got a distress call from my client that his house was invaded by the military, the soldiers," Ijeafor said. "I believe they went there for reasons best known to them - that reason is nothing more than to go and assassinate him." He accused the security officers of plotting to suppress Kanu and consequently arresting him.

Nigeria's military referred to the allegations that they had invaded Kanu's homestead as "baseless and mischievous." Kanu, a British and Nigerian citizen, is presently on bail on treasonable felony charges. His trial is set to resume next month in Abuja.

Calls for an independent Biafra have grown ever since Nnamdi Kanu was released on bail. During an exclusive one on one with DW's Adrian Kriesch, Kanu reiterated his demand for a referendum on the independence of Biafra. President Muhammadu Buhari has strongly rejected any attempts to divide Nigeria saying the unity of the country was "not negotiable."

Read more: After long absence due to ill health, Nigeria's President Muhammadu Buhari slams divisions, terror

Read more: Nigeria and the Biafran War: Ending the silence

More than one million Igbos died following the unilateral declaration of an independent republic of Biafra in 1967.

Nigeria's military urged to be cautious

Governor Okezie Ikpeazu of Abia State attributed the rising tension to the presence of soldiers. The Nigerian army is carrying out a military operation codenamed "Python Dance II" to tackle what it says is rising crime in the region.

However, video footage and pictures showing some military officers allegedly torturing pro-Biafra supporters have triggered anger, particularly on social media. The Nigerian army has promised to investigate the matter and punish those found guilty.

"As always we call on Nigeria's military, while carrying out their constitutional obligations, to respect the human rights of all Nigerians," Amnesty International spokesperson in Nigeria, Isa Sanusi said.

"They have their own rules of engagement and their own code of conduct; we are always calling on them to respect this code of conduct while they are out in the field." For Sanusi, no one should end up as a victim of human rights violations as a result of their [military] activities.

Read more:  Amnesty accuses Nigerian army of killing 150 Biafran protestors

In 2016, at least 150 Biafra supporters were killed at peaceful protests according to Amnesty International.  Those figures were however dismissed by the military and police.

cm/rg (AFP/Reuters)