Troops presented the men taken from the convoy as rebels
Civilians in eastern Democratic Republic of Congo have surrounded and stoned a UN convoy after it was stopped by soldiers searching for rebels.
The army took more than 20 men from the convoy, tied them up and presented them as fighters loyal to rebel leader Laurent Nkunda.
But the UN said the men were in fact pro-government Mai Mai militiamen.
Recent weeks have seen heavy fighting involving rebels, government troops, and pro-government militia.
The violence has triggered a humanitarian crisis, forcing an estimated 250,000 people to flee their homes.
Food aid arrests
Meanwhile, a journalist with UN-sponsored Radio Okapi has been buried in Bukavu, south of Goma.
Didace Namujimbo, 34, was shot in the back of the neck by unknown assailants after getting out of a UN vehicle, reports the AFP news agency.
FORCES AROUND GOMA
CNDP: Gen Nkunda's Tutsi rebels - 6,000 fighters
FDLR: Rwandan Hutus - 6-7,000
Mai Mai: pro-government militia - 3,500
Monuc: UN peacekeepers - 6,000 in North Kivu, including about 1,000 in Goma (17,000 nationwide)
DRC army - 90,000 (nationwide)
Source: UN, military experts
On Sunday, hundreds of people surrounded and threw stones at the UN convoy after army forces stopped it in Kibati, about 10km north of the provincial capital, Goma.
The UN force, Monuc, has been criticised for not doing enough to protect people from Gen Nkunda's Tutsi rebels while the army retreated during recent fighting.
Army troops had searched each vehicle and pulled out more than 20 men, before tying their hands and presenting them to local people as CNDP rebels loyal to Mr Nkunda.
But the UN said the men were from the Mai Mai pro-government militia and it was transporting them as part of a demobilisation process.
"There is a misunderstanding," UN spokeswoman Sylvie Van Wildenberg told the BBC's Network Africa programme.
"We were transporting Mai Mai elements and we don't know for which reason FADRC [Congolese army] assumed they were CNDP."
The BBC's Thomas Fessy in the region says the confusion may well show a lack of trust between government troops and the UN peacekeeping mission, which has been mandated to support them.
Earlier, officials in Goma said they had arrested several market traders for selling food aid.
Goma mayor Roger Rashiy said about 40 tonnes of aid was recovered, reports the AP news agency.
A World Food Programme spokesman said this was just 1% of food aid distributed in the region and was normal in all emergencies.
Gen Nkunda has said he is fighting to protect his Tutsi community from attack by Rwandan Hutu rebels, some of whom are accused of taking part in the 1994 genocide.