Nigeria has started prosecuting over 500 individuals suspected of being involved in militant attacks in one of the largest terrorism trials in the country.

The suspects are accused of supporting and sponsoring terrorism, especially in the north-east, where an insurgency by the Boko Haram Islamist group has been going on for 17 years.

Insecurity has since extended to most other regions of the West African country, and communities, particularly those in rural regions, are at the hands of mushrooming militant groups and gangs, which kidnap for ransom.

According to the attorney general, the mass trial commenced on Tuesday in a high court in Abuja, where 227 suspects were arraigned in the presence of 10 judges.

This year alone, hundreds of people have lost their lives in bombings and other attacks around Nigeria.

Few individuals ever face prosecution for terror attacks, and suspects end up being held in custody and losing several years of their lives without trial.

Gunmen killed at least 20 people in the western state of Niger on Wednesday, according to the AFP news agency. According to the residents, the attackers were raiding villages in Shiroro district, which is notorious for the activities of kidnapping gangs and Islamist militants.

The court session on Tuesday was a high security affair with the suspects being ferried in convoys that are heavily guarded and their movements under the supervision of the military, police and intelligence agencies.

The court was also attended by international observers such as human rights groups and the Nigerian Bar Association.

It has been alleged that the defendants participated in attacks primarily in Northern Nigeria, and others are accused of aiding militants by financing them, providing arms and supplies.

Five of the accused have already been given varying jail terms – from seven to 20 years – after pleading guilty to charges that included selling livestock, supplying food and information to militant groups.

“The magnitude of the operation indicated the determination of the government to address the issue,” Attorney General Lateef Fagbemi said.

He said that the federal government is determined to see that due process is applied, as those who perpetrate terrorism are brought to justice.

Security expert Bashir Galma, a retired major of the army, told the BBC that the trial, which is likely to run in phases, was a positive move and a landmark step towards combating terrorism in Nigeria.

He said, “for years Nigerians have been asking questions as to why they hold these suspects [in custody] rather than taking them to court to be charged with whatever they are suspected of doing.”

“This will be a relief to the people who have lost their loved ones, either killed or injured.”

The trial would also dispel rumours that suspects were routinely released after arrest “so that they can go back to their terrorism business”, the analyst added.

He, however, projected that a few of the accused may be released in the near future since they were arrested many years back – something that he said, “the judges will probably put into consideration.”