Mr Ekpa was arrested in Finland days after threatening to frustrate Nigeria’s general election, Finnish daily Helsingin Sanoma reported.
It was not immediately clear why Mr Ekpa was arrested or when he would be released, but the paper said the separatist provocateur was likely to face prolonged interrogations, with officers saying they were only doing their job on the matter.
The arrest comes as Mr Ekpa intensifies an attempt to frustrate the Nigerian presidential elections scheduled for February 25.
Mr Ekpa, 37, shot into prominence following the abduction of IPOB leader Nnamdi Kanu by Nigerian authorities in June 2021 — becoming the de facto leader of the secessionist movement.
He had declared a so-called sit-at-home edict for residents across the country’s South-East to stay away from polling centres or suffer violent consequences.
Nigerian authorities had also urged Finland to intervene and check Mr Ekpa’s inciting broadcasts from the safety of the European country.
It was unclear whether the police acted on Nigeria’s request or the widespread online clamour for the separatist agitator’s arrest by people of Igbo extraction, especially supporters of Peter Obi, an Igbo politician with the rising popularity and an improved shot at the presidency this cycle.