Mortar fire in eastern Democratic Republic of Congo has killed three Tanzanian soldiers who were part of a southern Africa force deployed to help government troops battling M23 rebels, officials said.The regional force sent soldiers to North Kivu province in December to help Kinshasa regain ground from the M23 militia in the lawless east.The force includes soldiers from regional military heavyweight South Africa, Tanzania and Malawi.”This unfortunate incident happened after a hostile mortar round had fallen near the camp (where) they were staying,” the 10-nation Southern African Development Community (SADC) said in a statement.It gave no further details about the incident.A source at the North Kivu governorate said the mortar attack struck last Thursday and a ceremony to honour the dead was held at SADC headquarters in the provincial capital Goma on Monday.A soldier from South Africa has also died in hospital while being treated for health problems, the SADC statement said.After several years of dormancy, the mostly-Tutsi M23 (March 23 Movement) group took up arms again in late 2021 and has seized vast swathes of North Kivu province.- Wracked by violence -The region has been wracked by violence in the decades since regional wars in the 1990s.The DRC, the UN and Western countries accuse Rwanda of supporting the rebels in a bid to control the region’s vast mineral resources, an allegation Kigali denies.The force suffered its first losses in mid-February when two South African soldiers were killed by mortars at Mubambiro camp, near the town of Sake, about 20 kilometres (12 miles) from the provincial capital, Goma.A Congolese security source, asking not to be named, said the Tanzanian casualties happened at the same camp.The force was to take over from an East African peacekeeping force, whose mandate was ended by Kinshasa which accused it of colluding with the rebels instead of fighting them.The UN mission in Democratic Republic of the Congo (MONUSCO) is also being wound down.The 15,000 UN troops deployed in the vast central African country started to leave in February at the request of the Kinshasa government, which considers them ineffective.The withdrawal is due to be completed by the end of the year.According to an internal UN document seen by AFP, M23 rebels have made new gains in the east after Indian UN troops abandoned positions near Goma.MONUSCO said in a note to staff that “the current security situation is becoming increasingly volatile as M23 has reached the northern outskirts of Sake,” a key town near Goma.The population of Goma has doubled to two million as refugees have fled the advance of the rebel group.Residents said that M23 and Congolese forces exchanged artillery fire throughout the weekend around Sake and the western outskirts of Goma.Â