Civilians facing bombs, thousands forced to flee and lost children – aid organisations have again sounded the alarm over the impact of escalating violence in eastern Democratic Republic of Congo, where fresh fighting erupted on Thursday.

Clashes between M23 rebels and pro-government forces that have gone on for more than two years have intensified in particular in North Kivu province.

In recent weeks “the increase in civilian casualties and the use of heavy weapons in populated areas, including in camps for displaced people, are alarming”, the International NGO Forum in DRC said in a statement.

The fighting has sparked massive displacement towards several areas, exacerbating the vulnerability of those forced to flee and the host communities, it warned.

“The situation requires urgent action to protect civilians and ensure humanitarian access,” added the Forum, which represents more than 120 international NGOs operating in DRC.

Save the Children said the renewed fighting between the rebels and government troops had displaced at least 150,000 people, more than half of them children, since February 2.

“Parents have reported that many children have been separated in the violence, although the number of lost children is unknown,” the charity said in a statement.

Around seven million people have been displaced in DRC, mostly in the east, which has been plagued by violence by armed groups for nearly 30 years, according to the United Nations.

Fighting resumed around Goma, the capital of North Kivu province, after a lull during the December 20 election which returned President Felix Tshisekedi to power for a second term.

Doctors without Borders, known by its French initials MSF, said the medical units it supported in North Kivu had seen a large influx of war wounded in recent days.

At the same time thousands were fleeing the latest armed clashes, it said.

On Wednesday, thousands of people arrived in Goma, fleeing violence in the town of Sake, about 20km (12 miles) away and strategically located on a major highway.

Six people were reported killed on Wednesday in Sake and many more injured, medical and security sources said.

Army spokesman General Sylvain Ekenge told reporters late Tuesday there had been “intense fighting” for control of a stretch of highway running between Sake and Minova, a small town in the neighbouring province of South Kivu.

Other clashes were reported north of Goma in Nyiragongo territory, pitting M23 rebels mostly against armed pro-government militias known locally as Wazalendo, and cutting off north-bound road traffic.