Hezbollah supporters gathered in the streets of Beirut on Tuesday after a UN tribunal filed indictments over the assassination of a former prime minister, prompting several schools to close as nervous parents withdrew their children from class.
Journalists reported seeing at least four gatherings of up to 30 people each, dressed in black and carrying hand-held radios.
One gathering was about 400 yards from the Grand Serail, the seat of government in downtown Beirut, and security officials closed the roads leading to the building.
Lebanese security officials confirmed the gatherings, which dispersed by late morning and appeared to be a show of force in the hours after a long-awaited indictment was released on Monday night over the death of former Prime Minister Rafik Hariri.
The indictment was sealed and its contents are not expected to become public for weeks. But the court is widely expected to accuse members of Hezbollah of being involved in the killing, something the Shiite militant group has insisted it will not accept.
Ghaleb Abu Zeinab, a member of Hezbollah's political bureau, said he was not aware of such gatherings.
"I cannot comment," he said.
The indictment, confirmed by the international court's headquarters in the Hague, is the latest turn in a deepening political crisis in Lebanon, where Hezbollah toppled the Western-backed government last week in a dispute over the tribunal.
The Iran and Syria-sponsored group fiercely denies any role in the killing and says the tribunal, jointly funded by UN member states and Lebanon, is a conspiracy by Israel and the United States.
Many fear the crisis could lead to street protests and the kind of violence that has bedevilled the country for years, including a devastating 1975-1990 civil war and sectarian battles between Sunnis and Shiites in 2008.