European Council President Charles Michel visited Libya on Sunday as the nation grapples with continuing instability and rising covid cases.
Rival factions in Libya agree on an interim presidential council to lead the country into elections in December.
The report accuses states including the UAE, Turkey, Jordan and Russia of funding rebel forces in defiance of the UN
As they return to the seas for the first time since April, rescue ship operators say migrants fleeing Libya's humanitarian crisis are undeterred by Europe's coronavirus outbreak
News of the missing boat comes amid criticism of the European Union's lack of rescue missions in the Mediterranean Sea.
Guterres said conflicts in Libya, Yemen and Syria were escalating as gains made in 2019 are reversed in 2020.