UNITED NATIONS (AP) — U.N. experts say they have “solid evidence” that members of Rwanda’s armed forces are conducting operations in volatile eastern Congo in support of the M23 rebel group, which is waging a major offensive in the mineral-rich region that has caused deaths and massive displacement of civilians.

In a new report to the U.N. Security Council, obtained Thursday by The Associated Press, the experts accused Rwanda’s forces of violating a U.N. arms embargo against Congo by their “direct intervention” into the country, either to support the M23 group or to conduct military operations against another armed rebel group, the FDLR.

Rwandan military members also violated sanctions by providing weapons, ammunition and uniforms to M23 rebels, the group of experts said.

Relations between Congo and its smaller neighbor Rwanda have been fraught for decades. Rwanda alleges that Congo gave refuge to the ethnic Hutus who carried out the 1994 Rwandan genocide that killed at least 800,000 ethnic Tutsis and moderate Hutus. Rwanda’s President Paul Kagame, a Tutsi, is widely credited with stopping the genocide.

Congo has accused Rwanda of supporting the M23, mainly comprising Congolese Tutsis, which Rwanda has long denied. And Rwanda has accused Congo of supporting the FDLR, a Hutu rebel group opposed to Tutsi influence, which Kinshasa denies.

The experts’ report comes at a time of worsening security in eastern Congo that led to a meeting between Rwanda’s Kagame and Congo’s President Felix Tshisekedi in Angola’s capital, Luanda, on July 6 and agreement to revive a Congo-Rwanda commission. A statement issued afterwards called for a return to normal diplomatic relations between Kinshasa and Kigali, a cessation of hostilities, and the “immediate and unconditional withdrawal” of the M23 rebel group from its positions in eastern Congo.

The U.N. special envoy for Congo, Bintou Keita, warned the Security Council in late June that during recent hostilities M23 conducted itself “increasingly as a conventional army rather than an armed group,” saying it possesses increasingly sophisticated firepower. She said this has put civilians, and U.N. peacekeepers charged with protecting them, under greater threat.

The U.N. experts said that despite almost 15 months of “continuous state of siege” in North Kivu and Ituri provinces in eastern Congo and military operations by Congo’s armed forces, Ugandan forces, and troops from the U.N. peacekeeping force known as MONUSCO, “the security and humanitarian situation in the two provinces has remained of great concern.” They singled out the deteriorating situation in the Rutshuru and Nyiragongo areas of North Kivu.

Attacks by M23 fighters have become more frequent, longer and stronger, and the territory under the group’s control “significantly increased,” causing massive displacement of civilians and indiscriminate shelling, the experts said. M23 combatants also “deliberately killed civilians” and adopted the tactic of attacking MONUSCO troops.

The experts said some Congolese army troops forged “ad hoc alliances” with local armed groups to fight against the M23 unilaterally or jointly with other Congolese troops. These armed groups were provided with weapons, ammunition and uniforms by some members of the Congolese army, they said.

The experts said the support to several Congolese armed groups, and cooperation with them, by members of the country’s armed forces in Rutshuru also violated the U.N. arms embargo.

Violations of international human rights and humanitarian law, including deliberate killings of children and civilians and indiscriminate shelling that killed civilians and damaged houses and schools, notably by M23, are also acts that can lead to sanctions, the expert group said.

Since M23 intensified its operations, the experts said it also documented with great concern “a sharp multiplication of hate speech and discourses inciting discrimination, hostility and violence” targeting Rwandan-speaking people, at times leading to violence against them.

The experts also reported on Uganda-based ADF rebels, who have been active in eastern Congo for decades and have killed thousands in the region since they resurfaced in 2013.

The ADF continues to expand its area of operations and continues to conduct attacks against civilians in the Beni region of North Kivu and southern Ituri, the expert group said

It said an explosion on April 7 in a bar in the Congolese army’s Katindo camp in Goma, which killed at least eight people, “was most likely planned and committed by ADF.”

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