The UN's Libya envoy pleaded with foreign actors to honor an arms embargo on the conflict-torn country as he said an attack on a Tripoli factory Monday may amount to a war crime.
Ghassan Salame accused unnamed countries of worsening the violence in Libya in a strongly worded address via video link to the United Nations Security Council in New York.
He said "external parties" were operating drone strikes that are increasing civilian casualties, adding that the growing use of experienced mercenaries was intensifying the conflict.
"The dangers and direct consequences of foreign interference are increasingly evident," said Salame, warning of a "race against time" to secure a peaceful resolution to the conflict.
Salame called for external actors to adhere to a UN arms embargo imposed on Libya since 2011.
He did not mention any names but a confidential report seen by AFP earlier this month found that Jordan, Turkey and the United Arab Emirates have regularly violated the embargo.
The year-long study found that the three countries "routinely and sometimes blatantly supplied weapons with little effort to disguise the source."
According to diplomats, Jordan was accused of having trained troops of Khalifa Haftar, a military strongman in eastern Libya who launched an offensive in April in a bid to seize Tripoli from fighters loyal to the Government of National Accord (GNA).
The United Arab Emirates -- another Haftar backer -- is suspected of using attack aircraft on behalf of his Libyan National Army (LNA) forces.
The UAE is suspected of involvement in a July 2 bombing of a detention center for migrants in a Tripoli suburb which left around 50 people dead.
Salame said in his briefing that LNA forces were increasingly using unguided bombs in airstrikes on populated areas of Tripoli.
"It is our judgement that the drone infrastructure and operations are facilitated by external parties to the conflict," he added, without naming names.
Salame said an attack on a biscuit factory in southern Tripoli Monday had killed 10 people and "may constitute a war crime."
Libya has been mired in chaos since a NATO-backed uprising that toppled and killed dictator Moamer Kadhafi in 2011.
The battle for Tripoli, which has come to a standstill on the ground after initial advances by Haftar's forces, has killed more than 1,000 people and displaced about 120,000 others, according to the UN.
Haftar is backed by Saudi Arabia, Egypt and the UAE, while Turkey and Qatar back his rival, the United Nations-recognized GNA.