President Omar al-Bashir of Sudan, who is wanted by the International Criminal Court, is in Libya for a two-day visit.
He was met by National Transitional Council chairman Mustafa Abdul Jalil at Tripoli airport on Saturday.
Abdul Jalil visited Khartoum in November. He has said Sudanese weapons and ammunition helped oust the late Colonel Muammar Gaddafi last year.
However, the Human Rights Watch group said that after several decades of brutal rule by Muammar Gaddafi, it is disturbing the new government in Tripoli is talking to another head of state accused of war crimes.
Bashir is wanted by ICC in The Hague on charges of orchestrating genocide in the Darfur region of Sudan.