Chad has sentenced 10 members of the Islamist militant group Boko Haram to death on terror charges, after a three-day trial in the capital N’Djamena.

The 10 were convicted over their roles in twin attacks on the capital in June, which killed at least 38.

The attacks were the first by the Nigerian-based group in Chad, which hosts the headquarters of a regional force set up to fight the militants.

In July, Chad reintroduced the death penalty for acts of terror.

Opposition and civil liberties groups have criticised the new anti-terror legislation, saying it could be used to curb civil rights.

The men were found guilty of charges including criminal conspiracy, killings, wilful destruction with explosives, fraud, illegal possessions of arms and ammunition, and using psychotropic substances, according to chief prosecutor Bruno Mahouli Louapambe, quoted in AFP news agency.

Among those convicted was Mahamat Mustapha, aka Bana Fanaye, the man described as the “mastermind” of the attack by Chad’s Interior Minister Abderahim Bireme Hamid.

The June attacks were followed by a blast at a market in the capital in July, which killed 15 people.

Chad has banned people from wearing the full-face veil following the bombings.

Boko Haram had previously threatened to attack Chad, after it sent troops to help Nigeria recapture territory from the militant group, mostly in Borno state.

Chad has been instrumental in helping Nigeria retake most of the areas Boko Haram had seized.