In a press conference in Kinshasa, the UN peacekeeping mission MONUSCO said 739 cases of breach of human rights were recorded in August, compared to 492 the previous month, leading to the death of at least 293 civilians.

Sixty-three women and 24 children were among the dead, according to the estimate, compiled by the UN's Joint Human Rights Office (UNJHRO) in the Democratic Republic of Congo.

Ninety-four percent of the documented cases in August occurred in the North Kivu and Ituri provinces.

These provinces have been placed under extraordinary "state of siege" measures since May aimed at quelling armed groups that have been roaming the region for more than a quarter of a century.

"Agents of the state" accounted for nearly 55 percent of the cases, which includes the extrajudicial killings of at least 40 civilians.

Armed groups were responsible for the other 45 percent of recorded abuses, although the number of killings attributed to them -- at least 253 -- was far higher.

UNJHRO was set up in 2008 to monitor human rights abuses, especially for women, children and vulnerable people, in DR Congo -- sub-Saharan Africa's biggest country.

Its chief, Abdoul Aziz Thioye, told reporters that the state of siege, under which senior civilian posts have been taken over by military or police officers, had enabled "some improvements in the security situation" but "many challenges remain".

In particular, he voiced concern for the districts of Irumu and Djugu, which have been targeted by the Allied Democratic Forces (ADF) -- a long-running jihadist group that has recently been linked to the Islamic State organisation.

"A new tendency" had emerged with the ADF, which was sharpening ancient disputes between ethnic communities by teaming up with one group against the other, Thioye said.

When the armed forces attack the ADF, the group responds by dispersing into small units and extending into a wider area, he said.

"The threat is very complex," he said.