Rwandan President Paul Kagame has denied allegations by UN experts that his country is continuing to support rebels in neighbouring Burundi.
Mr Kagame said the problems in Burundi originated from within the country, not elsewhere.
Burundi has suffered a violent political crisis since President Pierre Nkurunziza decided to run for a controversial third term last year.
It is exactly a year since Mr Nkurunziza survived a coup attempt.
Rwanda denied similar allegations about supporting rebels made in a previous UN-backed report in February.
Mr Kagame criticised the authors of the latest leaked report, which is due to be presented at the UN World Security Council later, saying their time would be better spent addressing countries' problems rather than exacerbating them.
The report obtained by Reuters news agency accuses Rwanda of providing training, as well as financial and logistical support throughout 2016 for rebels seeking to overthrow Mr Nkurunziza.
Already in bad shape, relations between the two countries deteriorated further in March after a former Rwandan minister died in jail in Burundi, having been arrested for espionage.
More than 400 people have died since the start of the crisis in April 2015 and at least 260,000 have fled the country in that time.