At least nine people, including seven children, were killed in the strike on the Mugunga camp in the eastern city of Goma on Friday.

The Congolese army and M23 blamed each other for the attack.

Rwanda, which borders DR Congo, is widely accused of backing the rebel group, which it denies.

The US State Department said Friday's attack came from positions held by the Rwanda Defence Force (RDF) and the M23 group.

A spokesperson said the US was "gravely concerned about the recent RDF and M23 expansion" in eastern DR Congo and called on both parties to "respect human rights and adhere to applicable obligations under international humanitarian law".

"It is essential that all states respect each other’s sovereignty and territorial integrity and hold accountable all actors for human rights abuses in the conflict in eastern DR Congo," they added.

Images circulating on social media showed bodies lying on the ground at the camp on Friday.

Most residents had fled there to escape fighting in their home towns and villages.

Lt Col Guillaume Njike Kaiko, a spokesman for DR Congo's army in the region, said the strike had come in retaliation for earlier Congolese attacks on Rwandan army positions.

President Felix Tshisekedi, who has spent several weeks abroad, will be returning to the central African country this weekend following the attack.

Rebel and government troops have both been accused in recent months of abuses against civilians as they vie for territorial control.

The latest strike comes days after M23 fighters claimed they had seized the town of Rubaya - an area which is at the heart of mining coltan used for making mobile phones and batteries for electric vehicles.

Meanwhile, a military court in Goma has sentenced eight DR Congo soldiers to death for "desertion" and "cowardice" when fighting rebel forces.

M23, formed as an offshoot of another rebel group, began operating in 2012 ostensibly to protect the ethnic Tutsi population in the east of DR Congo, which had long complained of persecution and discrimination.

UN experts have said that the group is backed by neighbouring Rwanda, which is also led by Tutsis, something that Kigali has consistently denied.

James Gregory