Representatives of Libya's interim government will join US Secretary of State Antony Blinken as well as the foreign ministers of France and Egypt at the UN-sponsored talks.
On China, which has been accused of repressing its minority Uyghur population and cracking down on rights in Hong Kong, and Russia, Raab said the "door was open" to better ties.
In a statement after the meeting, Mitsotakis said the two leaders "agreed on the immediate resumption of talks between Greece and Libya on the delimitation of the maritime zones".