Rwandan rebels have killed at least 50 civilians in May in the volatile east of the Democratic Republic of Congo, the United Nations said on Wednesday. Twenty-two of them died in an attack Monday in the village of Kamananga in Sud-Kivu province, the United Nations humanitarian agency OCHA said, blaming the Democratic Forces for the Liberation of Rwanda (FDLR) rebel group. \"The FDLR accuse the locals of collaborating with elements\" of a local militia, a statement said. \"Since the start of this month, at least 50 people -- including displaced persons -- have been killed by presumed FDLR members under similar conditions,\" it said. On May 5, at least 10 people -- including four women working in the fields -- were killed by the presumed rebels in another Sud-Kivu village. The FDLR is considered one of the main sources of instability in the east of the DR Congo, where several armed groups are still active. The rebels have been targeted by the Rwandan army in joint operations with the DR Congo army, which continues to track them. But the operations were suspended under the orders of President Joseph Kabila on April 11 after several former rebels integrated into the national army defected. These soldiers, formerly members of the rebel National Council for the Defence of the People (CNDP), mutinied to protest bad conditions, food and pay and to demand the full implementation of the 2009 accords. Following the defections, the FDLR has multiplied attacks in the region, in what many locals say is a bid to demoralise the Congolese army. On Wednesday, Human Rights Watch said rebel general Jean Bosco \"Terminator\" Ntaganda, who is wanted by the International Criminal Court for recruiting child soldiers was again forcing boys into military service. Between April 19 and May 4, troops serving Ntaganda forcibly recruited at least 149 boys and young men aged between 12 and 20 in Nord-Kivu province, the rights group said in a statement. HRW researchers interviewed witnesses and victims, and said at least seven boys had died in the fighting. At least 48 of those recruited were under 18 years old and of these, 17 were aged 15 or younger. HRW said one woman its researchers spoke to described how Ntaganda personally worked to recruit young soldiers in her village. \"Since you (villagers) have been with the government, you\'ve gotten nothing. Why not join me?\" HRW quoted the woman as saying. Ntaganda \"asked us to give our children, our students, to him to fight. He came to our village himself,\" she added. The ICC classes the recruitment of children under 15 a war crime.