ABUJA, Nigeria: More than 300 terrorism suspects were convicted by a court in the Nigerian capital of Abuja in a mass trial that spanned four days.

Many suspects pleaded guilty to charges brought against them by the Nigerian government in the mass trial that began on April 7.

Many of them have now been sentenced to prison terms of up to 20 years after appearing before a panel of 10 judges.

Nigeria's attorney general said that a total of 508 cases were brought, and 386 of them resulted in convictions. Speaking to journalists after the mass trial, he said they had succeeded in delivering justice and that this sends a strong message.

Nigeria is facing a serious and complicated security crisis, especially in the north. There has been an insurgency for over a decade, along with several armed groups that carry out kidnappings for ransom. The conflict in the northeast has been going on for many years.

Some of the main militant groups include Boko Haram and a breakaway faction linked to the Islamic State group, called Islamic State West Africa Province. Another IS-linked group, Lakurawa, operates in northwestern areas near the border with Niger.

There are also frequent clashes over land and grazing between mostly Muslim Fulani herders and mainly Christian farming communities in the north-central and northwestern regions.

In addition, criminal gangs involved in kidnapping for ransom are active.

According to the United Nations, the insurgency in the northeast has caused many deaths and forced large numbers of people to flee their homes.