GOMA, Democratic Republic of Congo (Reuters) -At least nine people, including seven children, were killed on Friday in a strike at a displacement camp in the eastern Congolese city of Goma, a local official and a military spokesman said.

It was not immediately clear what kind of explosive device was used or who was responsible for the attack.

A two-year offensive by the Rwanda-backed rebel group M23 has moved closer to Goma in recent months, prompting thousands to seek refuge in the city from surrounding areas.

The head of the Lac Vert district where the incident occurred, Dedesi Mitima, told Reuters he had seen the bodies of seven children and two men at the camp.

Several other people were wounded and the death toll could rise further, Mitima added.

Lieutenant-Colonel Guillaume Njike Kaiko, a spokesman for the Democratic Republic of Congo's (DRC) army in the region, said the strike had come in retaliation for earlier DRC attacks on Rwandan army positions which he said had destroyed arms and ammunition. He gave no details about the attack on the camp.

Congo's government spokesperson Patrick Muyaya, in a message on X, also blamed the Tutsi-led M23 for Friday's attack.

An M23 leader, Bertrand Bisimwa, also writing on X, accused the Congolese authorities of deliberately attacking the camp in an attempt to "manipulate" the international community.

In February, a strike blasted a crater into the ground in the same Lac Vert neighbourhood. Nobody was hurt in that attack, but it underscored the seriousness of the threat to Goma, a strategic urban hub in the conflict-ridden eastern DRC.

(Reporting by Yassin Kombi, Djaffar Sabiti, Fiston Mahamba and Ange Kasongo; Writing by Anait Miridzhanian, Editing by Timothy Heritage and Gareth Jones)