ABUJA (Reuters) - Nigeria has convicted the first person to be brought to justice for the Chibok girls kidnapping, a crime that made Islamist militant group Boko Haram notorious around the world, the justice ministry said.

As part of a mass trial of suspected members of the group, 35-year-old Haruna Yahaya was sentenced to 15 years imprisonment for his role in the abduction of more than 200 girls from their school in the northeastern town of Chibok in 2014.

The ministry said Yahaya had confessed to participating in the kidnapping after being forced to join the group. He said he had lost count of the number of people he had killed.

The man was one of more than 50 convicted since the trial of hundreds of suspects resumed on Monday, the ministry said on Wednesday.

“It’s going according to plan with over 50 cases dispensed in two days,” said ministry of justice spokesman Salihu Othman Isah.

The Chibok abduction by the group, whose name in the Hausa language roughly translates as “Western education is forbidden”, attained international attention and sparked a campaign called #BringBackOurGirls.

More than 20,000 people have been killed and 2 million forced to flee their homes in the northeast of Africa’s most populous nation since the jihadist group began an insurgency in 2009.

Abba Umar, a 22-year-old man, was jailed for 60 years on Tuesday.

The justice ministry, in an emailed statement, called him an “unremorseful sect commander” who “remained adamant to his ideology despite all the efforts by the defense counsel to convince him to have a change of heart”.

Suspects have appeared in open court after rights groups criticized the use of secret trials in October.

Last year the ministry of justice said 45 people with Boko Haram links had been convicted and jailed. A further 468 suspects were discharged and 28 remanded for trial.