Chad's chief prosecutor announced the death sentences late Friday after a short closed-room trial before Chad's Special Criminal Court at a secret location. Mahouli Bruno, speaking on state television, said those "condemned will be shot."

The accused include 30-year-old Cameroonian Mahamat Mustapha, also known as Bana Fanaye, who Chadian authorities had accused of being the mastermind behind the N'Djamena attacks.

Boko Haram is an Islamist group based in northern and eastern Nigeria blamed for an insurgency that has claimed thousands of lives since 2009.

Chad, Cameroon and Niger, which had all suffered attacks attributed to Boko Haram, are in the process of forming a 8,700-strong regional force together with Nigeria, comprising troops and police to tackle the insurgents.

The suicide attacks on June 15 targeted a training center and a police building in N'Djamena, Chad's capital, which lies less than 100 kilometers (60 miles) from the border with Nigeria.

Attacks on remote villages in Nigeria

A civilian defense group in northeast Nigeria said on Friday it had learned that Boko Haram extremists had killed 28 people during attacks on two remote villages.

The first attack occurred on Tuesday night at Marfunudi in Borno state and left 24 dead. Extremists struck Thursday in the village of Kafa, killing four more residents.

The Nigerian army said it had found and destroyed an improvised explosives-making facility in Borno state and arrested three suspected Boko Haram members.

Earlier this year, Chadian and Nigerian troops drove extremists out of some 25 towns. The insurgents have since resorted to hit-and-run tactics.

Doctors Without Borders said on Friday that 75,000 refugees from Niger, Nigeria and Chad had been displaced from their homes due to attacks near Lake Chad.

ipj/ng (AFP, Reuters)