Queues built at banks that reopened after a one-week closure on Tuesday, with police deployed at branches and tight restrictions imposed on hard currency withdrawals and transfers abroad.

Lebanon has slid further into economic crisis since the protests erupted on October 17.

The political situation has been deadlocked since Saad al-Hariri resigned as prime minister on October 29, with no progress towards a deal on a new government.

Gunfire was heard as a group of several dozen protesters forced two SUVs with official number plates to turn back as they approached the parliament on Tuesday morning, broadcaster's footage showed.

The vehicles sped away after they were struck by demonstrators chanting "Out, out, out!"

Authorities later announced the session had been postponed indefinitely.

The agenda of the parliamentary session had included re-electing members of parliamentary committees and discussion of a controversial amnesty law expected to lead to the release of hundreds of prisoners.

Speaker Nabih Berri had already postponed the session last week due to security concerns.

The security forces fanned out before dawn in central Beirut, shutting down roads around parliament with barbed wire in what proved to be a failed attempt to prevent the protesters blocking the session.

Police scuffled with one group trying to use a cable to remove a barbed wire barricade.

"How are they holding a session and not responding to the people? Those that are in the session have nothing to do with us and it's not what we asked for," said a protester who gave her name as Maria.

The protests have been fuelled by perceptions of corruption among the sectarian politicians who have governed Lebanon for decades and are blamed for leading the country into its worst economic crisis since the 1975-90 civil war.

Australian Associated Press