Over 2,300 Boko Haram militants to be tried in Nigeria

The defendants have all been picked up and held in detention since the start of the conflict eight years ago, which has left at least 20,000 dead in the country's remote northeast.

To date, just 13 people have been put on trial and only nine convicted for their links to the terrorists, according to official figures.

The most high-profile current case is that of Khalid Al- Barnawi, a leader of the Boko Haram offshoot Ansaru, who is charged with the abduction and murder of 10 foreign nationals.

Nigeria's justice ministry announced the start of the trials at the end of last month, saying four judges had been assigned and that defendants would have legal representation.

Some 1,670 detainees at a military base in Kainji, in the central state of Niger, will be tried first followed by 651 others held at the Giwa barracks in the capital of the northeastern Borno state, Maiduguri.

"It's the first significant trial of Boko Haram suspects," said Matthew Page, a former US State Department analyst and a specialist on Nigeria.

But he said that while "positive" it was still a "very small step", as many of the detainees had been held in custody for years, without access to a lawyer or ever having appeared before a judge.

Amnesty believes the mass trials of Boko Haram suspects were the result of international pressure on the Nigerian government.