"Security agents made a breakthrough on Friday in the fight against terrorism by arresting Khalid al-Barnawi, the leader of Ansaru terrorist group in Lokoja," military spokesman Brigadier General Rabe Abubakar said.
"He is among those on the top of the list of our wanted terrorists," he added.
Lokoja is the capital of Nigeria's central Kogi state.
The US Department of State in June 2012 named Khalid al-Barnawi alongside Boko Haram leader Abubakar Shekau and Ansaru founder Abubakar Adam Kambar.
Al-Barnawi assumed the leadership of Ansaru following the death of Kambar in a military raid on his hideout in Kano in March 2012.
Ansaru, a splinter group of Boko Haram, specialising in high profile killings and attacks on global interests, is linked to Al-Qaeda in the Islamic Maghreb.
He was the alleged mastermind of the March 13, 2011 kidnap of a Briton and an Italian, both construction engineers, in northern Kebbi state.
The two hostages were killed in a failed rescue bid by British and Nigerian Special Forces in the northern city of Sokoto on May 7, 2012.
Trained in Afghanistan and Algeria, he was also behind the January 26, 2012 kidnap of a German construction engineer -- Edgar Raupach -- in the northern city of Kano.
The German was killed along with four captors in a botched rescue operation by Nigerian troops on May 30, 2012 at a hideout on the outskirts of Kano, where the group is mostly based.
With the emergence of Ansaru, Barnawi's faction became independent of Boko Haram but still maintained ties.
The group also claimed responsibility for the kidnap of a French engineer, Francis Collomp, in northern Katsina state in 2012. He escaped almost a year later.
