The LRA are notorious for abducting children and mutilating victims
More than 400 people have been killed by Ugandan rebels in the Democratic Republic of Congo in attacks since Christmas day, aid agency Caritas says.
The head of Caritas in DR Congo told the BBC some 20,000 people had fled to the mountains from the rebels, who have denied carrying out the attacks.
An eyewitness told the BBC that five people in Faradje had their lips cut off by Lord's Resistance Army fighters.
They were told that it was a warning not to speak ill of the rebels.
The armies of Uganda, South Sudan and DR Congo carried out a joint offensive against the rebels in mid-December after LRA leader Joseph Kony again refused to sign a peace deal.
The LRA leader, who has lived in a jungle hideout in north-eastern DR Congo for the last few years, is wanted by the International Criminal Court for war crimes and crimes against humanity.
Uganda's government had been involved in lengthy peace negotiations with the LRA, hosted by the South Sudanese government.
But Mr Kony has demanded that arrest warrants for him and his associates be dropped before any agreement can be struck.
'Hacked to death'
News of the attacks in north-eastern DR Congo began to come out after the weekend when the Ugandan army accused the LRA of hacking to death 45 civilians in a Catholic church near Doruma.
Bruno Mitewo, head of the Catholic aid agency, says that from information they have collated from their parishes on the ground, more than 400 civilians have died in the attacks.
He said that in Faradje 150 civilians had died, almost 75 people in Duru and 215 in Doruma.
The victims had been hacked to death and forced into fires, he said.
"All villages were burned by rebels... we don't know where exactly the population is because all the villages are empty," he told the BBC.
"We have almost 6,500 displaced who are refugees in the parishes of the Catholic Church around the city of Dungu, more than 20,000 people displaced are running to the mountains," he said.
Those who were hiding in the bush and forest were mainly the young, as the LRA tends to kidnap children and recruit them as fighters, he said.
An eyewitness in Faradje said the people who had their lips cut off were being treated for their injuries.
Earlier, LRA spokesman David Nekorach Matsanga told the BBC that the allegations that the massacres had been perpetrated by LRA fighters were untrue.
He said rebel units were not in the areas concerned and said a group of LRA defectors who joined the Ugandan army may have been responsible.
Many thousands of Congolese villagers fled their homes after LRA attacks near Dungu in October.
Countries from Uganda to the Central African Republic have suffered 20 years of terror inflicted by the LRA.
Tens of thousands of children have been abducted to be fighters and sex slaves.
Uganda's government said the joint offensive had destroyed some 70% of the LRA camps in DR Congo.
BBC Africa analyst Martin Plaut says that Mr Kony's force is relatively small - about 650 strong - but the difficulty is that when it is hit, it scatters and then regroups.