BEIRUT — Public anger against cash-strapped banks boiled over in crisis-hit Lebanon where demonstrators armed with metal rods, fire extinguishers and rocks attacked branches in protest at controls that have trapped the savings of ordinary depositors.

The Red Cross said on Wednesday that at least 37 people were injured in an overnight showdown during which protesters smashed windows of banks and scuffled with security forces in the capital's Hamra commercial district.

Police said 59 people were detained, making it one of the largest wave of arrests since Lebanon's anti-government protest movement began on Oct. 17 demanding a complete government overhaul.

As the movement nears the start of its fourth month, banks have become a prime target of demonstrators who charge them with driving the country toward its worst economic crisis since the 1975-1990 civil war.

On Wednesday morning in Hamra, a banking hub, almost every branch was left with smashed display windows, destroyed ATMs and graffiti-daubed walls, after what the Association of Banks condemned as a "savage" onslaught.

Banks opened their doors despite the wreckage, as cleaners wiped spray paint off walls and workers replaced window fronts.

With some ATMs destroyed beyond repair, passers-by looked on in astonishment at the aftermath of the night-time assault on banks.

"There is a lot of anger," Alia said in front a damaged branch. "You have to go to the bank twice to withdraw just $200."

In other areas of Beirut, demonstrators blocked a key flyover and gathered outside a police station where demonstrators have been detained, under the watchful eye of security forces.

Banks have since September arbitrarily capped the amount of dollars customers can withdraw or transfer abroad, in a country where the greenback and the Lebanese pound are used interchangeably.

Although no formal policy is in place, most lenders have limited withdrawals to around $1,000 a month, while others have imposed tighter curbs.

Sparked by a grinding liquidity crunch, the controls are increasingly forcing depositors to deal in the plummeting pound, amounting to what experts are calling a de facto banking "hair cut".

The local currency has lost over a third of its value against the dollar on the parallel market, plunging to almost 2,500 against the US dollar over the past week.

The official rate was pegged at 1,507 Lebanese pounds to the greenback in 1997.

Demonstrators accuse banks of holding their deposits hostage while allowing politicians, senior civil servants and bank owners to transfer funds abroad.

Banks have as a result transformed into arenas of conflict, where shouting and tears abound, as depositors haggle tellers to release their money.

Compounding the situation, debt-burdened Lebanon has been without a government since Saad Hariri resigned as prime minister on Oct. 29 under pressure from the anti-government protests.

Lebanon's under-fire politicians have yet to agree on a new Cabinet line-up despite the designation last month of Hassan Diab, a professor and former education minister, to replace Hariri.

The designated premier has pledged to form a government of independent experts — a key demand of protesters — but acknowledged last week that some parties were hindering his attempts.

Authorities on Wednesday condemned the night-time attacks and called for legal action against the perpetrators.

Hariri termed the rampage "unacceptable," while Parliament Speaker Nabih Berri questioned whether the aim was to "destroy the country."

But the UN envoy to Lebanon, Jan Kubis, blamed politicians for the turmoil.

"Politicians, don't blame the people, blame yourselves for this dangerous chaos," he said in a strongly-worded statement, accusing them of standing by and watching the economy "collapse".

Piling extra pressure on the premier-designate, demonstrators have returned to the streets since Saturday after a brief lull over the end-of-year holidays.

They staged a demonstration Tuesday outside Diab's house at the launch of "a week of wrath".

But Hamra was the main target of Tuesday night's demonstrations, with protesters hurling stones and fire crackers at security forces who responded with tear gas.

They splattered walls with graffiti, vandalized street signs and sparked a blaze outside the Association of Banks head office.

Showing no sign of backing down, demonstrators called for another demonstration outside Lebanon's central bank building later Wednesday.

Main arteries were closed in north and east Lebanon and several schools stayed closed after the latest unrest. — AFP