A total of 144 people were arrested, including 29 minors, in the August crackdown on a religious sect that called demonstrations against the United Nations' presence in the war-torn eastern province of North Kivu.

The minors were sent to a tribunal for children and all acquitted, lawyer Didier Balume told AFP.

But the remaining 115 were put on trial on September 1 before a military court in the province, accused of taking part in an "insurrectional movement" and killing a policeman.

The court on Monday sentenced the main accused, Efraimu Bisimwa, to death.

Sixty-two others received sentences ranging from 10-20 years the remaining 52 were acquitted, the lawyer said.

The death penalty is often handed down in the Democratic Republic of Congo, but it has not been applied for 20 years and is systematically commuted to life imprisonment.

"My clients are in reality survivors of a massacre," committed by the military, said Balume.

"All pleaded not guilty. How can you explain that people who are victims end up in the dock?"

The lawyer also deplored the fact that the tribunal imposed harsher sentences than the prosecution called for -- notably 20 years for Bisimwa.

The crackdown saw 57 people killed, according to the latest official toll, and has led to renewed tensions in the North Kivu capital of Goma, an area plagued by violence by armed groups.

In the aftermath, the government quickly announced the arrest of several soldiers and promised justice would be served.

Last week, a military court sentenced a DR Congo army officer to death and handed 10-year prison terms to three other soldiers over the killings in Goma.