Officials in protest-hit Lebanon on Monday promised to take measures to deter attacks on security forces by alleged "infiltrators" during the violence over the weekend that injured hundreds of people.

Lebanon has been rocked by mostly peaceful anti-government rallies since October 17, but the protests turned violent on Saturday and Sunday amid political deadlock and an ever-deepening economic crisis.

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Over the weekend, demonstrators, who had called for a "week of rage", lobbed stones, firecrackers and street signs at riot police, who fired tear gas and rubber-coated bullets to clear a road leading to Parliament.

The escalation saw more than 540 people wounded on the two sides and came as wrangling delayed the formation of a new government to replace that of Prime Minister Saad Hariri, who quit last year in the face of street protests.

On Monday afternoon, President Michel Aoun presided over crisis talks on the violence between the caretaker interior and defence ministers, as well as the chiefs of the military and security agencies.

Participants accused "infiltrators" of attacking security forces and vandalising property, and discussed security measures to "deter" further offences and protect peaceful protesters, government sources said after the meeting, without disclosing what measures would be taken.

Aoun met security chiefs to work out a plan for deterring violent groups that "security services have detailed information on" while protecting property and peaceful protesters, the sources said.

'Brutal force'

In a show of defiance, demonstrators who said they took part in the weekend protests responded online using the Arabic hashtag "The Infiltrator Is Me," disclosing their full personal details.

They also accused security forces of firing rubber bullets at the eyes of protesters in other Twitter posts, as rights groups and the United Nations criticised police over the crackdown.

Human Rights Watch accused riot police of "launching tear gas canisters at protesters' heads, firing rubber bullets in their eyes and attacking people at hospitals and a mosque".

The UN also condemned the use of force.

"Violence from protesters and vandalism are, of course, unacceptable," said UN spokesman Stephane Dujarric.

But the vast majority of protesters were peaceful "and they need to be protected", he added.

A 22-year-old protester, who asked not to be named for security reasons, said he was severely beaten by security forces until he was bleeding from the head.

"Four of them were beating me with batons," said the man, who has been in the hospital since Saturday. "Then they dragged me on the ground before they started kicking me. One of them slammed the base of a tear gas launcher against my mouth, another jabbed my face."

Politicians have failed to agree on a government or an economic rescue plan since the unrest pushed Hariri to quit as prime minister on October 29, paralysing efforts to recover from a crisis that has shattered confidence in banks and raised investor concerns about its ability to repay steep foreign debt.

Last month, little-known former minister Hassan Diab was designated prime minister with the backing of armed Shia group Hezbollah and its allies.

But a deal on the cabinet formation is yet to be announced, with political factions squabbling over ministerial posts and portfolios.