DORUMA, Congo Feb 9 (Reuters) - An offensive against Ugandan Lord's Resistance Army rebels in Congo has had catastrophic consequences for civilians but must go on to drive out the rebels, the U.N. humanitarian chief said on Monday.
Lord's Resistance Army (LRA) fighters have killed nearly 900 people in northeastern Democratic Republic of Congo, mostly since the start of a multinational campaign on Dec. 14 led by Ugandan forces.
"It's true that the humanitarian consequences have been catastrophic," U.N. Emergency Relief Coordinator John Holmes told reporters in Doruma, where at least 13,000 civilians have taken refuge after a spate of attacks by the rebels.
"I think they need to see the operation through. I don't know how long that will take...but I think there is no point in putting a premature end to it," Holmes said.
The decision lay with the Congolese and Ugandan governments, he said.
"We, meanwhile, will try to pick up the pieces as best we can."
The U.N. says 700 people, including 540 children, have been abducted to become fighters, porters or sex slaves, while others have been orphaned and traumatised.
"They beat my mummy and daddy's heads with pieces of wood. I hid in a bush by the road and watched them kill my parents," said Abango, a boy of 6, in a centre for traumatised children.
The U.N. peacekeeping force in Congo said in late January that so far, only 40 LRA fighters had been killed. The reclusive LRA leader Joseph Kony, a self-proclaimed mystic who has waged a 20-year rebellion in northern Uganda, has vanished.
"WE LAUGH TO STOP CRYING"
Holmes addressed a crowd of more than 1,000 displaced people in the palm tree-lined square by Doruma's church, one of the few brick-built structures in a town where most people live in mud huts or, for the latest arrivals, shelters of banana leaves.
Many of those gathered wore rags and others dressed themselves in leaves to demonstrate their plight.
"No to the violence, No to the bloodbath in our territory," read a banner held up by one person.
"We laugh to stop ourselves from crying," read another.
Mibie Sangbayo Zachee, said he fled here when LRA rebels attacked his village, Diagbe, 50 km (31 miles) to the south.
"They killed 15 people in my family. They crushed their heads with machetes. They broke all their bones," Zachee said.
"Once the Ugandan (army) arrived, that made the situation worse. But if they go home without getting their brothers out of the bush, we won't be happy," said the greying 53-year-old.
The world's biggest peacekeeping force has come under criticism for not doing more to help protect civilians.
"They stay in one place, in Dungu. They stay in the base, and most are engineers," Medecins Sans Frontieres spokeswoman Avril Benoit said.
"There is no protection, as far as we can see, substantially being offered by the United Nations."
(Writing by Alistair Thomson; Editing by David Lewis and Angus MacSwan)