Tukur Mamu had been leading negotiations with bandits for the release of the Abuja-Kaduna train passengers kidnaped in March.
Mr Mamu was intercepted in Cairo on Tuesday while on his way to Saudi Arabia.
The Islamic scholar asked the secret police to “take him (Mamu) to court” to face trial.
Mr Mamu was linked to international terrorists organisations whose members he planned to meet outside the country.
Mr Mamu was detained at the Cairo International Airport for 24 hours and is being repatriated to Nigeria, many outlets are reporting.
