Lebanon's pro-Syrian President Emile Lahoud has rejected a proposal for a United Nations-backed court probe into the murder of former Prime Minister Rafik Hariri.

Lahoud said Saturday he is returning the draft for review by the Cabinet, which approved the planned court last month. He said the Cabinet's decision was not valid because it came after six ministers from the pro-Syrian opposition resigned.

Hezbollah leaders have called mass demonstrations on Sunday to press for more participation by opposition parties in the government.

Prime Minister Fuad Siniora has accused the militant group of threatening a coup against his U.S.-backed government.

On Friday, U.S. Secretary of State Condoleezza Rice expressed concern that extremist forces and Syria and Iran are trying to destabilize Lebanon. She said such pressure on Mr. Siniora's government cannot be tolerated.

Some information for this report was provided by AFP and AP.