Hundreds of thousands of people have fled inter-ethnic violence in northeastern areas of the Democratic Republic of Congo in the past two weeks, local authorities and the UN said Tuesday.

The UN refugee agency voiced deep concern over a flare-up in violence in DRC's volatile Ituri Province, which it said had seen "multiple attacks" involving the Hema and Lendu groups since early June.

Agency spokesman Babar Baloch told journalists in Geneva the violence had forced more than 300,000 to flee their homes, voicing fears "this escalation could engulf large parts of the province".

Ituri governor Jean Bamanisa Saidi said the number of displaced could be as high as 400,000.

"We are overwhelmed with this surge in displacement," Saidi told AFP, stressing the urgent need to ensure the safety of the displaced and "stop the violence".

Local officials last week said at least 50 people had been killed in a matter of days in Ituri, while other sources put the death toll from the inter-ethnic violence at over 70.

The cause of the latest flare-up was not immediately clear, but it occurred in a region where tens of thousands died in clashes between the Hema and Lendu ethnic groups between 1999 and 2003.

Baloch pointed out that attacks between the two communities had also displaced some 350,000 in late 2017 and early 2018, "but the situation had calmed".