Democratic Republic of Congo President Felix Tshisekedi on Tuesday renewed accusations that Rwanda is fanning rebel groups in his country during an address at the United Nations.
"Despite my goodwill and the Congolese people's outstretched hand for peace, some of our neighbours find no way to thank us other than supporting armed groups in the east of the Democratic Republic of Congo," Tshisekedi said in a speech to the General Assembly.
"This is currently the case with Rwanda which, in defiance of international law and the UN Charter ... once more committed aggression in March with direct incursions by its armed forces into the Democratic Republic of Congo."
Tshisekedi said that Rwanda had provided "massive support both in war materiel and troops" to M23 rebels, which have been increasingly active in eastern border areas and which he brands a "terrorist group".
The M23 are a mostly Tutsi force that had been defeated in 2013, but took up arms again late last year.
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Tshisekedi accused the Rwandan military of supporting the M23 in shooting down a UN peacekeeping helicopter in March in which six Pakistanis, a Russian and a Serb were killed.
"Rwanda's involvement and responsibility is no longer debatable in the tragedy that my nation and compatriots are living through in zones occupied by the Rwandan army and their M23 allies," Tshisekedi said.
Rwanda has denied the charges and vowed to defend its territory. President Paul Kagame is due to speak at the United Nations on Wednesday.