A UN source said on Friday that the peacekeepers were members of the Bangladeshi contingent and that nine bodies were recovered.
Kemal Saiki, a spokesman for the UN mission in the Democratic Republic of Congo, said the attack took place on Friday morning in the mineral-rich Ituri district, where the UN has deployed 4800 peacekeepers.
"There have been casualties in the UN forces, including some fatalities," he said, but could not give further details.
The UN force in Ituri is made up of four contingents of 850 soldiers each from Pakistan, Bangladesh, Morocco and Nepal.
The district is one of Congo's worst troublespots, where ethnic militias have killed 50,000 civilians since 1999.
The former Zaire is struggling to recover from a wider five-year war that at one stage sucked in six neighbouring countries and, according to an international aid agency, has killed nearly four million people.
About one third of the world's biggest UN peacekeeping mission is based in Ituri but attacks on civilians remain frequent.
Clashes between militia during the last two months alone have displaced some 70,000 civilians, aid workers say.