A Nigerian court has convicted 45 Boko Haram members in the largest mass trial in the terrorist group's history.

The country's information minister says the 45 people were sentenced to between three and 31 years in prison. Another 468 suspects were released, but the court ordered that they undergo de-radicalization programs.

These are the first results of the mass trials that began early this week at a military barracks in northern Nigeria.

The closed-door proceedings have raised the concerns of human rights groups about whether the trials of more than 1,600 people will be fair.

Nigeria is trying to show it is making progress against the group that has killed more than 20,000 people during its eight-year insurgency.

Military detention facilities are overcrowded with thousands of suspected members.