Lebanon's teetering government was expected Monday to approve a belated economic rescue plan as the nation prepared for a fifth day of mass protests against the ruling elite.

A proposed tax on mobile messaging applications last week sparked a spontaneous, cross-sectarian mobilisation that has brought Lebanon to a standstill and put the entire political class in the dock.

Hundreds of thousands of protesters gathered in central Beirut and other cities Sunday to demand better living conditions and the ouster of a cast of politicians who have monopolised power and influence for decades.

Euphoric crowds partied deep into the night, leaving all political and sectarian paraphernalia at home to gather under the national cedar flag, dancing to impromptu concerts and chanting often hilarious anti-establishment slogans.

Lebanon's economy has been on the brink of collapse for some time and the initial grievances of the protesters were over proposed tax hikes.

But the demonstrations have evolved into a massive push to unseat ruling dynasties widely seen as corrupt beyond redemption, and Hariri's 11th-hour rescue plan was met with disdain on the street.

The cabinet was due to meet on Monday morning and expected to approve a raft of measures, including the scrapping of new taxes and a sweeping privatisation programme, among others.

"This was not a paper suggested to get people off the street," a senior cabinet official insisted.