A confidential UN report is said to accuse Jordan, Turkey, and the United Arab Emirates of regularly violating the arms embargo on Libya.
It reportedly says forces from Chad and Sudan were also involved, but with less impact.
The report by UN experts, seen by the French news agency AFP, says that both sides of the Libyan conflict receive weapons, technical support, and foreign fighters.
AFP says the substantial report is due to be discussed by the UN Security Council at the end of the month.
On Wednesday, BBC Arabic reported, quoting a confidential UN investigation, that a fighter plane from a foreign country was behind a July’s attack killed 53 migrants and injured 130.
The UN described it as a potential war crime.