HELSINKI, Finland (AP) — Police in Finland said Thursday they had detained five suspects in connection with deadly violence in southeastern Nigeria and were seeking a court extension of the detentions.

The police did not identify the suspects, only saying that a dual Finnish-Nigerian citizen, born in the 1980s, was under criminal investigation.

However, Simon Ekpa, a Nigerian linked to the Biafran separatist movement, lives in Lahti, where the Päijät-Häme District Court will consider a request from the Finnish National Bureau of Investigation to keep the suspects in custody.

Ekpa is one of the leaders of the Indigenous People of Biafra separatist group that is demanding the creation of an independent Biafra state from the troubled southeast region of Nigeria.

“The police suspect that the man (under investigation) has furthered his efforts from Finland in such a way that has resulted in violence against civilians and public authorities and in other crimes in South-East Nigeria,” Detective Chief Inspector Otto Hiltunen said in a statement.

The suspect “carried out this activity by campaigning, for example, on his social media channels,” Hiltunen said.

The secessionist campaign in southeastern Nigeria dates back to the 1960s when the short-lived Republic of Biafra fought and lost a civil war from 1967 to 1970 to become independent from the West African country. An estimated 1 million people died in the conflict, many from starvation.

Nigerian authorities have accused Ekpa of using social media to instigate violence by his followers in Nigeria, many of them young people.

Police in Finland said the investigation involves international cooperation.

Nigerian authorities did not immediately respond to requests for comment.

For many years Nigeria, Africa’s most populous nation, with at least 210 million people, has been wracked by violence related to the activities of armed extremist groups. Most recently, social protests were held over a worsening cost-of-living crisis and alleged bad governance.