Four arrest warrants have been issued by the UN-backed tribunal investigating the 2005 murder of Lebanon's former Prime Minister Rafik Hariri, the court said.
Hariri's son, Saad, welcomed the indictments and described them as a "historic moment" for Lebanon.
Local reports say the warrants name senior members of the Shia militant and political group Hezbollah. Hezbollah has repeatedly denounced the tribunal and vowed to retaliate.
Divisions over the Special Tribunal for Lebanon (STL), based in The Hague, have thrown the country into political turmoil and prompted fears of sectarian unrest.