ABUJA, Nigeria (AP) — A court in Nigeria on Thursday sentenced a top militant leader of an al-Qaida-linked group on the country’s most-wanted list to 15 years in prison for illegal mining and using the proceeds to fund terror attacks.

Mahmud Muhammad Usman, who headed the Ansaru group, had pleaded guilty to the charge of engaging in illegal mining to procure arms for his militant group. It was the first conviction on a total of 32 charges brought against him by the Nigerian government.

Usman will remain in the custody of the Nigerian secret police while his trial continues. The other charges mostly include other counts of terrorism and the handling of illegal arms.

Usman was arrested last month along with fellow militant leader Mahmud al-Nigeri in an operation involving several Nigerian law enforcement agencies.

Usman’s group is accused of carrying out the 2022 attack on a prison in Abuja, Nigeria’s capital, that saw nearly 900 inmates escape, including dozens of Ansaru members. The group is also said to have been behind the attack on Niger’s uranium facility in 2013.

Nigeria, Africa’s most populous country, faces multiple security threats with dozens of armed groups taking advantage of the limited security presence in the rural communities to carry out attacks on villages and along major roads.

Despite military assaults on the groups, they have continued to expand their operations and carry out routine attacks. This year, Boko Haram has mounted a major resurgence.

The United States recently approved a potential $346 million weapons sale to the country that authorities have said will boost the fight against insecurity.