United Nations Secretary General Ban Ki-moon has placed phone calls to the presidents of both Rwanda and Congo, as a mutiny in the eastern DR Congo intensifies, amid accusations that Kigali is backing the rebels, according to dpa. The mutineers, known as the M23 and comprising largely of former rebels who were integrated into the Congolese army in 2009 but defected in April, are allegedly linked to Bosco Ntaganda, a renegade general wanted by the International Criminal Court. "Stressing the need do everything possible to dissuade the M23 from making further advances and to cease fighting immediately, the Secretary-General urged Presidents (Paul) Kagame and (Joseph) Kabila to pursue dialogue in order to defuse tensions and bring an end to the crisis," Ban's spokesman said in a press release late on Wednesday. A UN report released last month accuses Rwanda - which has historic ties to Ntaganda and other ethnic Tutsi rebel movements in the eastern Democratic Republic of Congo - of arming and aiding M23. Ban expressed "grave concern" over the report, according to his spokesman. The rebel group has managed to defeat the Congolese army in several recent battles and seized towns along the border with Uganda. The UN peacekeeping mission in the massive Central African country has boosted its presence around Goma, the main city in the region, fearing an attack. M23 this week set up a political wing, as the group pushes for negotiations with Kinshasa, which the rebels accuse of not respecting the 2009 peace deal. The fighting between the rebels and the Congolese army has displaced tens of thousands of people in recent months. Ministers and technical experts at the African Union, currently holding a summit in Ethiopia, spent many hours on Wednesday deliberating the crisis in the Congo, in an effort to diffuse tensions in the volatile region. Uganda has warned that the crisis could spill over and destabilize East Africa. Congo's last civil war, which ended in 2003, drew in eight nations on the continent and left more than 5 million people dead, mostly from disease and hunger.