Greek Foreign Minister Nikos Dendias met with Libyan National Army (LNA) leader Khalifa Haftar at the Foreign Ministry in Athens on Friday.
Footage shows Dendias welcoming Haftar, before they sit down with other officials.
Addressing the press, Dendias said "our common European position recognises the absolute nullity and non-existence of the memoranda signed between the Sarraj government and Turkey."
The two agreements focus on the Turkish military deployment to Libya and on the delineation of the two countries' maritime borders.
The Greek foreign minister added that Greece is ready to help "with the participation in those forces that are necessary for a truce or with the participation of Greek forces in the European operation of imposing an embargo on weapons and mercenaries transfers to Libya."
The LNA leader is also expected to meet with Greek Prime Minister Kyriakos Mitsotakis on Friday.
Haftar's visit to Greece takes place two days before the Berlin Libya conference. Both him and the rival leader of the UN-backed Government of National Accord (GNA), Fayez al-Sarraj, are to attend the event.