Hundreds of thousands of people have rallied in central Beirut in a massive Hezbollah-led protest against Lebanon's government.
Protesters on Friday waved Lebanese flags in a show of unity, but they also wore the yellow baseball caps of Hezbollah.
Thousands of protesters also staged an indefinite sit-in outside the heavily-barricaded government offices, with Prime Minister Fuad Siniora holed up inside.
They say they will not move until Mr. Siniora resigns.
The Shi'ite militant group Hezbollah is demanding a new national unity government.
Prime Minister Siniora has vowed to resist efforts to oust him.
He says there is no way to remove a government except through parliament.
In Washington, a State Department spokesman, Tom Casey said the United States is very concerned that Hezbollah and its allies, with the support of Iran and Syria, are trying to destabilize Lebanon.
The spokesman said the U.S. is committed to supporting Lebanon's democratic government and its efforts to re-establish Lebanese sovereignty.
Shi'ite support for Hezbollah increased following the 34-day war earlier this year between the militant group and Israel.
Six ministers from the Hezbollah and Amal parties quit the government in November because their demands for more power were not met.
Tensions have been high in Beirut since the November 21st assassination of anti-Syrian Christian politician Pierre Gemayel.