The US ambassador on Friday declared support for Lebanon's all-party talks, saying the dialogue that starts Monday was an opportunity for the country to resolve the tension generated by Hizbullah's demand for a bigger role in government.

Earlier this week Hizbullah, which has two ministers in the coalition Cabinet, threatened to call mass demonstrations unless Prime Minister Fuad Saniora recast his government to give the militant group and its allies a veto on key decisions.

The White House accused Hizbullah and its Syrian and Iranian sponsors of seeking to topple Saniora's government.

All the major factions are due to take part in round-table talks on Monday, convened by the speaker of parliament, Nabih Berri. A political ally of Hizbullah, Berri has proposed the talks focus on the formation of a "national unity" government and a new electoral law.