Hundreds of people converged on Lebanon's Sunni bastion of Tripoli on Tuesday to take part in a 'day of rage' over the likely appointment as prime minister of Hezbollah-backed tycoon Najib Mikati.
Convoys of vehicles and buses could be seen heading toward the northern seaport city from early morning for a demonstration scheduled to begin at 10:00am (0800 GMT).
Schools and many stores shut down in Tripoli and surrounding areas as security forces deployed in force.
Similar protests were planned in other regions, including in Beirut and the mainly Sunni southern coastal city of Sidon.
Sunni MPs called the protests after accusing Hezbollah of having staged a "coup" as it became clear the Shia party and its allies had secured enough votes in the 128-seat parliament to impose billionaire Sunni tycoon Najib Mikati to head the next government.
Under Lebanon's complex power-sharing system, the country's prime minister must be a Sunni.
Mikati's likely appointment to the premiership has angered the Sunni community who see it as a bid by the Iranian-backed Hezbollah to sideline outgoing premier Saad Al-Hariri -- Lebanon's most popular Sunni leader -- and essentially take control of the government.
Protests broke out on Monday in mainly Sunni regions, including Tripoli, Sidon and several west Beirut neighbourhoods with demonstrators burning tyres and chanting "Sunni blood is boiling!" There were no reports of injuries.
"The street rejects Hezbollah's candidate," said the headline in the Arabic-language daily Al-Mustaqbal, owned by Hariri's family.
It referred to Hezbollah chief Hassan Nasrallah as Lebanon's "supreme leader," in an allusion to clerical rule in Iran.
"Easy majority for Mikati's appointment ... and Hariri responds by announcing 'Day of Rage'!" was the response from the daily As-Safir, close to Hezbollah.
The US embassy near Beirut issued a warning to its citizens to take safety measures.
"The embassy urges US citizens to remain alert to local security developments and to be vigilant regarding their personal security," it said in a statement.
"Major and minor roads may become blocked with no advance notice," it added. "Even peaceful gatherings can turn violent and spread with little or no warning."
Hezbollah on 12 January brought down Hariri's Saudi- and Western-backed government after a long-running standoff over a UN-backed probe into the 2005 assassination of ex-premier Rafiq Al-Hariri, Saad's father.
The group has said it believes members of the party will be implicated by the Netherlands-based Special Tribunal for Lebanon, which it has denounced as part of a US-Israeli conspiracy.
Washington, which considers Hezbollah a terrorist organisation, on Monday expressed "great concerns" at the likelihood of the party playing a major role in the new government.
"We would have great concerns about a government within which the Hezbollah plays a leading role," US State Department spokesman Philip Crowley said.
Lebanese President Michel Sleiman on Tuesday was to wrap up two days of consultations with all the groups in parliament before appointing the new premier.
Although Hezbollah has said its coalition would seek to include its rivals in the new government, Hariri has ruled out joining a cabinet controlled by the Shia party.
Hariri's coalition controlled a majority in parliament but with Mikati leaving the coalition and influential Druze leader Walid Jumblatt also siding with Hezbollah, his camp lost its majority.