The four members of the tribal Mai-Mai militia were convicted for their role in the "assassination" of three Indian UN troops last August, Captain Bernard Kangela, military prosecutor of the court in Goma, said.
The court in Nord-Kivu province acquitted four other militia members citing lack of evidence.
Three Indian UN soldiers were hacked to death and seven wounded during a surprise attack by 60 Mai-Mai militia on a UN base in Nord-Kivu at Kirumba, 30 kilometres (about 20 miles) south of Rwindi.
Court president Major Rene Zingi said that the Mai-Mai member sentenced to death denied the charges but added that "the others identified him as their leader."
He added that the UN mission in the DR Congo MONUSCO was not acting as a plaintiff in the case.
Although courts issue death penalties in the country, no executions have taken place since President Joseph Kabila came to power in 2001.
The Mai-Mai are local clan militias that changed sides in successive wars that wracked the DR Congo between 1997 and 2003. They have remained under arms and remain one of the sources of instability in the east.
Most Mai-Mai groups consider themselves to be local defence militias. They believe in witchcraft and before going into battle drink special potions that they believe will protect them from harm.
In some parts of Nord-Kivu and Sud-Kivu provinces, the Mai-Mai have become allied to Hutu rebels of the Democratic Forces for the Liberation of Rwanda (FDLR), and Kinshasa's troops have been hunting both since early 2009.
Eastern DRC has been wracked by instability for more than a decade due to the presence of armed groups which routinely carry out widespread looting, murders and rape of hundreds of women and children.
MONUSCO, earlier known by its French acronym MONUC, has been present in DRC since late 1999 and its new mandate to consolidate peace runs out at the end of the month.
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