The U.N. said nine of its peacekeepers were killed in an ambush in the volatile northeastern Congolese district of Ituri on Friday morning. A spokesman for the mission said they were ambushed by unknown gunmen as they were on patrol. The losses are the heaviest the U.N. mission has suffered since it was set up there in 1999.

Nine Bangladeshi peacekeepers were killed in an ambush on Friday morning while they were patrolling the Democratic Republic of Congo's volatile Ituri district, the United Nations mission said.

The peacekeepers were attacked by militiamen who opened from all sides in a well planned ambush, while they were on patrol east of Bunia, capital of the mineral-rich district of Ituri.

It was not yet clear if there were any more injuries or missing among the Bangladeshi peacekeepers.

Fighting between ethnic militias has killed at least 50,000 people in Ituri since 1999 and the U.N. mission has nearly one third of its 16,000 peacekeepers based in the district.

The U.N. has called the attack premeditated and accused armed groups who terrorize the local population of carrying out the killings, adding that it would not deter the peacekeepers from neutralizing the militias and protecting civilians.

Some analysts believe the attack may have been carried out in retaliation for the arrest of nearly 30 Lendu militiamen by U.N. forces earlier in the week.

But a spokesman for the mission said it was too early to say which of the armed groups was responsible.

U.N. soldiers are regularly attacked as they patrol the lawless east, but Friday's death toll is the highest the mission has suffered since the mission was launched in 1999, to try an end years of fighting in Congo.

Peace deals concluded in 2003 led to the installation of a transitional government in Kinshasa. But much of the east remains in the hands of armed groups who continue to prey on the local population and exploit Congo's mineral riches.

As a result, the war continues to simmer. Aid agencies say some 70,000 civilians have been displaced by fighting in Ituri during the last two months alone.

The conflict kills 1,000 people every day, mostly from hunger and disease, on top of the 3.8 million that have already died since it began in 1998.