Missing pro-Biafran separatist leader Nnamdi Kanu gave a radio broadcast on Sunday saying he was in Israel, suggesting he owed his survival to the Jewish state.
Kanu, a former London estate agent, heads the Indigenous People of Biafra (IPOB) movement and the outlawed pirate radio station Radio Biafra but has not been seen in public since September last year.
He maintains the Igbo people, who are in the majority in southeast Nigeria, are a lost tribe of Israel and it is his mission to lead them to the promised land of Biafra.
There had been fevered speculation that Kanu was in Israel after a video live-streamed on Friday via the Facebook accounts of his known associates appeared to show him praying at the Western Wall in Jerusalem, sparking questions over how he had managed to leave Nigeria.
Kanu is facing treason charges in his homeland and had been on bail at the time troops were deployed to his home city of Umuahia in Abia state, southeast Nigeria, in September 2017.
He then failed to show at his trial in the capital, Abuja, sparking speculation as to his whereabouts.
In Sunday's broadcast on Radio Biafra, Kanu declared: "I'm in Israel".
"I owe my survival to the State of Israel," he added, referencing the country's Mossad spy agency but without specifying what kind of support Israeli authorities may have given him.
But he vowed to return to his homeland and called on his followers to boycott upcoming elections in Nigeria.
"I will be back soon in the land of Biafra and I will bring hell with me," he said.
"IPOB will liberate Biafra and we will not take part in any elections until we get a referendum, it is not negotiable, we will do it by any means," he added.
A previous unilateral declaration of independence by the Igbo people in 1967 sparked a brutal 30-month civil war that left more than one million dead.
Questions have been raised about how Kanu was able to get to Israel, as he had to surrender his Nigerian and British passports after his arrest.
In Friday's video the man at the Western Wall bore a clear resemblance to Kanu and was dressed in sandals, white trousers, a white Jewish prayer shawl and skull cap.
Kanu's younger brother, Prince Emmanuel Kanu, told AFP the footage was of his brother and was shot on Friday. He also spoke to him directly and said he was "fine".