UNITED NATIONS - The resumption of fighting in an eastern Democratic Republic of the Congo (DRC) province has killed and wounded civilians and restricted aid operations, UN humanitarians said on Tuesday.

The UN Office for the Coordination of Humanitarian Affairs (OCHA) said its local partners reported at least four civilians were killed and 15 injured in the flareup in the Masisi territory of North Kivu province. It also disrupted humanitarian efforts in the area to determine the kind of aid needed.

However, in South Kivu, local officials reported schools in Kalehe territory, about 65 kilometers north of the provincial capital, Bukavu, are gradually reopening. Schools had closed several weeks ago as fighting exposed schoolchildren and teachers to massive human rights violations.

Humanitarian partners of OCHA reported that unexploded ordnance remains a problem in many areas affected by recent fighting, including two schools in the city of Minova, about 150 kilometers north of Bukavu.

The Rwanda-supported M23 rebel group in recent weeks advanced south from its North Kivu stronghold, taking a swath of territory including the North Kivu capital of Goma, on Lake Kivu and at the border with Rwanda.

As for UN peacekeepers, Jean-Pierre Lacroix, the head of the world body's peace operations, expressed concern for the UN's mission in the DRC, known as MONUSCO, said Stephane Dujarric, spokesman for UN Secretary-General Antonio Guterres.

During a visit to South Sudan, Lacroix said MONUSCO faces limitations in areas controlled by M23 but continues to protect civilians and reduce violence in other areas, safeguarding hundreds of thousands of civilians daily.

Lacroix stressed in a news conference that there is no military solution to the DRC crisis, noting if hostilities cease, the UN stands ready to actively support a ceasefire.