MPs from north and east Uganda, worst hit by a 17-year brutal rebellion, are boycotting parliament until the security situation improves.
Many children leave their homes at night for fear of abduction
The 34 MPs accused the government of not taking the conflict seriously.
Last week, a senior United Nations said the humanitarian situation in northern Uganda was worse than anywhere in the world, even Iraq.
Lord's Resistance Army rebels are notorious for abducting children to be sex slaves and fighters.
Before walking out, MP Dr Okullo Epak read a statement detailing the situation, in which he said that 150 people had been killed in the past 10 days.
He accused the army of sending soldiers to the Democratic Republic of the Congo instead of protecting civilians in the north and east.
"These children who are being abducted because they are not being protected, at the end of the day, they are being mowed down by the UPDF fighters (army)," said MP Otto Odonga MP for Aruu, one of the worst affected areas.
Cecilia Ogwal, MP for Lira, scene of several recent attacks, said President Yoweri Museveni should call for international help or resign, reports The Monitor newspaper.
But Mr Museveni told the BBC that the LRA had no capacity to take power.
MP Otto Odong says the army is not protecting civilians
"Their motive is rural banditry... stealing chickens, young girls and so on," he told the Focus on Africa programme from the eastern town of Soroti.
LRA commander Brigadier Sam Kollo, who said he was also speaking from Soroti, told the BBC's Network Africa programme by telephone that the LRA controlled Kitgum, Gulu and Lira districts, except for the main towns.
"We are not defeated," he said.
He also denied committing atrocities against civilians, saying they were fleeing the fighting in general, not LRA attacks.
Meanwhile, a pro-government militia in southern Sudan has accused the LRA of killing 17 civilians in areas near the Ugandan border.
"The LRA are now killing our people, not only the Ugandans, and our fellow southerners and Equatorians in particular are the victims," said South Sudan Defence Force (SSDF) Commander Martin Kenyi.
The LRA were based in southern Sudan until the government allowed the Ugandan army onto Sudanese territory to flush them out last year.
However, the LRA responded by moving back into Uganda and increasing their attacks.
Some 1.3m people have been displaced by the conflict.