Abuja - The security agency said on Sunday it had made significant breakthroughs in the fight against Boko Haram and arrested 20 prominent members of the militant Islamist group accused of orchestrating deadly attacks.
President Muhammadu Buhari has made halting Boko Haram's six-year-old insurgency a priority, but a Reuters tally shows the militants have killed more than 700 people in bomb attacks and shootings since he came to office on May 29.
In the latest violence, around 56 people were killed by suspected Boko Haram gunmen at a village in northeastern Borno state on Friday night, Borno state governor Kashim Shettima said late on Saturday.
The Department of State Services (DSS) said on Sunday that 20 "notable commanders and frontline members" of the jihadist group had been arrested in Lagos, Kano, Plateau, Enugu and Gombe states between July 8 and August 25 this year.
The DSS said it had arrested those suspected of coordinating attacks earlier this year in the northern cities of Potiskum, Kano and Zaria, as well as the central city of Jos, adding that a number of them had made confessions.
"This followed the rounding up of notable commanders and frontline members of the notorious group from different parts of the country," DSS spokesman Tony Opuiyo said in a statement.
Providing an unusual level of detail, the DSS said one of those arrested, Usman Shuaibu, had confessed to leading a team of nine militants which planned several attacks. Others were accused of ordering attacks, preparing bombs and strapping explosives to suicide bombers.
"The arrest of Usman Shuaibu, aka Money, and the core members of his cell, stemmed the spate of bombings by the extremist sect," said Opuiyo.
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Boko Haram's campaign to create a state adhering to strict Islamic law in the northeast of Africa's most populous country has left thousands dead and forced around 1.5 million people to flee their homes since 2009.
The insurgents scattered earlier this year after an army counter-offensive, but have since returned to a strategy of selective attacks in which they have bombed or fired on targets in public places such as markets and places of worship.
Opuiyo said the geographical spread of the arrests suggested the militants were moving beyond their usual targets in the northeast to other areas, including Lagos state.
On Saturday, the DSS said it had uncovered a spy cell run by militants at the international airport in the capital Abuja, apparently aimed at selecting targets for attack.
Buhari has been working with neighbouring states to set up an 8,700-strong regional military task force to fight the insurgency. (Additional reporting by Lanre Ola in Maiduguri; Writing by Alexis Akwagyiram; Editing by Clelia Oziel/Ruth Pitchford)