Britain said there was "credible and compelling" evidence of Rwandan support for the M23 rebels in the Democratic Republic of the Congo, who have seized the eastern city of Goma.
In a joint statement on Thursday, the UK's Department for International Development and the Foreign Office said the allegations contained in a UN report "will necessarily be a key factor in future aid decisions to the government of Rwanda".
Justine Greening, the international development secretary, is to decide in mid-December whether to release a further £21m in aid to Rwanda
Long dubbed a "donor darling", Britain suspended some of its general budget support - aid directly to the government - in July before making the controversial decision to reinstate it in September, a move backed by Downing Street and the Foreign Office. Last week, Greening told MPs "all options were on the table" regarding the future of aid to the country.
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