Key parties have jostled over ministries since a legislative vote in May, as officials and foreign donors warned that a delay would aggravate the country's economic troubles.
The row has worsened a standoff between Berri, a Shia, and Aoun, a Maronite Christian, that threatens to ignite sectarian tensions in the run-up to a parliamentary election in May.
Lebanese President Michel Aoun said earlier this week that Hariri, who abruptly announced his resignation while in Saudi Arabia on November 4, was being held hostage by Riyadh.
Lebanese President Michel Aoun said on Sunday that Saad al-Hariri's freedom was being restricted in Riyadh, the first time the Lebanese government has publicly declared its belief that Saudi Arabia is holding its prime minister against his will.
Lebanon's president called on Saudi Arabia on Saturday to clarify why Lebanese Prime Minister Saad al-Hariri could not leave the kingdom and return home.
Saad al-Hariri's resignation stunned Beirut's political establishment, brought down the coalition government and sparked a new political crisis.
Hundreds of Palestinian protesters clashed with Israeli soldiers Friday in the powderkeg West Bank city of Hebron on the anniversary of a 1994 massacre carried out by a far-right Jewish settler.