Battled-hardened Chadian troops in pick-up trucks scour the bush in northern Nigeria, the scene of regular attacks by Islamist group Boko Haram.

Standing before a cache of weapons, pickup trucks and motorcycles captured from Boko Haram, Chadian army spokesman Agouna Azem said two prisoners had been brought to the base. One, nicknamed "The Butcher", was accused of beheading or slashing the throats of five people.

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Gambaru: A man the Chadian military say they have taken for belonging to insurgent group Boko Haram Emmanuel Braun/Reuters
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A prisoner, suspected of being a member of insurgent group Boko Haram, sits with his arms tied behind his back in Gambaru, NigeriaEmmanuel Braun/Reuters
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A boy, who the Chadian military say is the son of a killed Boko Haram fighter, stands with soldiers in GambaruEmmanuel Braun/Reuters

At their base in the town of Gambaru, Chadian soldiers paraded a war prize: a tank. "It belongs to Boko Haram. The Chadian army took it from them," Bermandoa said.

Chad said it killed 207 Boko Haram militants in fighting this week and seized large quantities of small arms and ammunition and two pick-up trucks.

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A Chadian military general inspects an armoured vehicle that they say Boko Haram had taken from the Nigerian militaryEmmanuel Braun/Reuters
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The logo of insurgent group Boko Haram is seen on the cracked windscreen of an armoured vehicle that the Chadian military say they destroyed in battleEmmanuel Braun/Reuters
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Weapons that Chadian military say they took from Boko Haram are seen in GambaruEmmanuel Braun/Reuters
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Chadian soldiers drive past the body of a man they say was a Boko Haram fighter killed in battle in Gambaru, NigeriaEmmanuel Braun/Reuters
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The body of a man, believed to be a Boko Haram fighter killed by the Chadian military, lies in a field in GambaruEmmanuel Braun/Reuters

Niger, Cameroon and Chad have launched a regional military campaign to help Nigeria defeat the Boko Haram insurgency, which aims to carve an Islamic emirate out of northeastern Nigeria.

Nigeria has come under criticism for not doing enough to drive Boko Haram out of its northern territories. Chad says it has had no contact with Nigerian forces on the ground and that they never fought alongside them.

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A Chadian soldier fixes his headscarf on a military vehicle in GambaruEmmanuel Braun/Reuters
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A Chadian soldier rides on a pickup truck next to a bag of rocket-propelled grenadesEmmanuel Braun/Reuters
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Chadian soldiers drive to the front line in the war against the insurgent groupEmmanuel Braun/Reuters
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A Chadian soldier wears charms for protection near the front line during battle against insurgent group Boko HaramEmmanuel Braun/Reuters
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Chadian soldiers drive near the front line in the war against Boko Haram in Gambaru, NigeriaEmmanuel Braun/Reuters