Two Serbian Embassy staff members were kidnapped on Sunday in Libya's coastal city of Sabratha, the Foreign Ministry said. It named the pair as Sladjana Stankovic, a communications officer, and Jovica Stepic, a driver.
"The ministry is making utmost efforts to gather information and secure the safe return of our citizens," the statement said, adding the foreign ministers of Serbia and Libya had discussed the situation.
No reason was given for the seizure and Serbian diplomats in Libya were not immediately reachable for comment.
A Serbian government official in Belgrade, who asked not to be named, said: "It appears it was an ambush, a shooting."
Libya has fallen into turmoil with its internationally recognised government and elected parliament on one side and a self-styled administration holding Tripoli on the other, each backed by regional, tribal or Islamist armed factions.
Belgrade has diplomatic relations with Libya's internationally recognised government, based in Tobruk. It previously maintained ties with the administration of Muammar Gaddafi until he was ousted in 2011.