COTONOU (Reuters) - Nigerian activist Sunday Adeyemo, imprisoned in Benin since last year for allegedly plotting an insurrection in Nigeria, has been released under judicial supervision, one of his lawyers said on Tuesday.

       Adeyemo, more commonly known by his nickname Sunday Igboho, belongs to the Yoruba ethnic group and rose to prominence with calls for herdsmen from the Fulani ethnic group to be driven out of Yoruba lands in southwest Nigeria.

       He was arrested last July at Cotonou airport while on his way to Germany, after a Nigerian security agency said it had found a stockpile of weapons at his house.

       He was released on Monday evening for health reasons, with the condition that he cannot leave Benin, said one of his lawyers, who requested anonymity until a news conference is held.

       Only his close entourage will be allowed access to his house in Benin's commercial capital Cotonou, which will be under police surveillance, the lawyer said.

       Igboho's arrest was seen as a sign of intensifying efforts by the Nigerian government to go after people seen as a threat to national security, even beyond Nigerian borders.

       It came shortly after separatist leader Nnamdi Kanu, from the Igbo ethnic group rooted in southeast Nigeria, was transferred to Nigeria in disputed circumstances. Kanu and his lawyers say he was detained and abused in Kenya before an illegal transfer, which Kenya and Nigeria denied.

       Earlier media reports said Nigeria was seeking Igboho's extradition, but the status of that request was unclear. The Nigerian authorities have not responded to multiple requests for comment on Igboho's case.

       (Reporting by Allegresse Sasse and Pulcherie Adjoha; Writing by Nellie Peyton; Editing by Estelle Shirbon)