Violence has worsened since talks to end a 19-year-old war in northern Uganda stalled earlier this year, prompting warnings that attacks are likely to increase unless the government takes urgent action to revive the negotiations.
In the first Lord's Resistance Army (LRA) raid on Thursday, rebels wielding axes and guns killed 16 people and seriously wounded several others at the Koch-Goma camp near Gulu. Six of them died in hospital.
Residents at the camp about 10km southwest of the main northern town of Gulu said the rebels struck early in the morning as their victims tended crops near their huts, changing their usual tactic of attacking at night.
"The rebels know they are losing, so they are trying to show the world they exist by desperately attacking innocent civilians," army spokesman Lieutenant Tabaro Kiconco said, reiterating a common refrain by the army after LRA attacks.
In another attack later on Thursday, a vehicle carrying civilians and troops was ambushed by rebels who opened fire on it near Kalongo in Pader district, bordering Gulu.
About 1.6 million people have
been displaced by the violence
"Three people were killed, including one soldier," local member of parliament Morris Latigo said.
"The vehicle was set on fire and several passengers ran off into the bush. Some of them haven't come back, so we don't know whether they have been abducted."
The LRA, led by self-styled prophet Joseph Kony, is notorious for kidnapping thousands of children to use as fighters and sex slaves.
Rebels have killed and kidnapped dozens of people in recent weeks. Ugandan troops say they shot dead 84 LRA fighters last month alone.
The rebels are rarely available for comment on reports of attacks.
About 1.6 million northerners shelter in refugee camps because of the war, rendering them dependent on food aid and paralysing farming in what was once the country's breadbasket.
The LRA has given no clear account of its aims beyond opposition to President Yoweri Museveni and an ambition to liberate the northern Acholi tribe - the ethnic group that suffers the most from its atrocities.
Museveni is being urged by big donors, such as Britain and the United States, to reopen talks. They say he has agreed in principle there should be another meeting between mediators and the LRA, but he is widely believed to prefer a victory on the battlefield.