Beirut, Lebanon - Prime Minister Saad Hariri has set a 72-hour deadline for his coalition partners to come up with solutions for Lebanon's economic crisis, as Friday's protests against austerity measures devolved into violence for a second day.

The protests, which broke out over government plans for new taxes, are the most serious challenge to Hariri's national unity government which came to power less than a year ago.

Hariri, in an address to the nation, blamed parties in his coalition for obstructing reforms to Lebanon's debt-laden economy.

"I'm giving our partners in government a very short deadline - 72 hours that can give us a solution that can convince us, the people on the streets and our international partners," he said, describing the country's economic malaise as "unprecedented" and "difficult".

As Hariri spoke, protesters waving Lebanese flags in Beirut's Martyr Square continued to call for the resignation of the country's political leadership, including Hariri, President Michel Aoun, Parliament Speaker Nabih Berri, and Foreign Minister Gebran Bassil.

Demonstrators, who are angry over plans to impose new taxes amid rising costs of living, chanted "Revolution! Revolution!" and "The people demand the fall of the regime". They also accused Lebanon's top leaders of corruption, and called for the country's strict banking secrecy laws to be lifted so that state funds stolen over the decades can be returned to the treasury.

"Thief, thief, Michel Aoun is a thief," some chanted, looking around nervously.

In Lebanon, insulting the president can land you in jail.

The peaceful demonstration devolved into clashes late on Friday, as police used tear gas to disperse protesters at the Riad al-Solh Square.

Protesters also took to the streets in the eastern Bekaa Valley and in Tripoli, Lebanon's second-largest city, where local media said that several protesters were wounded when a legislator's bodyguards opened fire on a crowd.

Riots were also reported in the Roumieh and Zahle prisons.

Earlier on Friday, Bassil, the foreign minister and president's son-in-law, in an address to protesters, also blamed other political parties for blocking reforms, but said that "any alternative to the current government would be far worse".

The demonstrations began on Thursday after the cash-strapped government announced plans to impose new taxes, including on WhatsApp voice calls. Overnight on Friday, protesters blocked streets across the country by burning tyres, and in some areas set fire to buildings and vandalised shops.

Amid the unrest, banks, shops and schools closed operations on Friday, and Saudi Arabia said it was evacuating its citizens from the country.

"Everyone is tired of this, the situation is horrible, people have no money, the people are falling apart, and all they give us is taxes, taxes, taxes," said Samir Shmaysri, a 39-year old hairdresser from Beirut.

"There's no reform process to even hope for the situation to get better."

The outpouring of anger prompted the Lebanese government to scrap plans for taxes on WhatsApp calls, but the measure did little to placate protesters.

"We want to change the situation in the country, that's it," said one protester who was blocking a road with a flaming rubbish bin near Beirut's Ras al-Nabaa area, just outside downtown.

"We've tried being peaceful, it hasn't worked."

The man had a wooden club with one charred end in his right hand. Next to him, another young man was busy reblocking a road with smouldering rubbish bins and burning tyres, after a Lebanese army vehicle briefly opened it to pass through.

Randa, who brought her young nephew to Friday's protest, said it was her first time on the streets.

"It's not a matter of whether it's fitting or not for a child his age," the university teacher said, as the Lebanese national anthem rang out from speakers being her.

"Everyone needs to come down," she said. "I feel that there is no partisan inclination to the protests. The intentions are pure."