PARIS, March 24, 2023 (BSS/AFP) - Protesters clashed with French security forces Thursday in the most serious violence yet of a three-month revolt against President Emmanuel Macron's hugely controversial pension reform.

Almost 150 police were injured and scores of protesters arrested nationwide, the government said, as a day of protests descended into chaos in several cities including Paris, where protesters lit fires in the historic centre of the city.

The uproar over the imposition of the reform -- which the government chose to push through without a parliamentary vote -- has turned into the biggest domestic crisis of Macron's second term in office.

It also threatens to cast a shadow over King Charles III's visit to France next week, his first foreign state visit as British monarch. Unions have announced fresh strikes and protests for Tuesday, the second full day of his trip.

In the southwestern city of Bordeaux, which King Charles is due to visit on Tuesday, the porch of the city hall was briefly set on fire.

- Trash set alight -

The numbers in Paris and other cities were higher than in previous protest days, given new momentum by Macron's refusal in a TV interview Wednesday to back down on the reform.

Police and protesters again clashed on the streets of the capital during a major demonstration, security forces firing tear gas and charging crowds with batons.

Some protesters lit fires in the street, setting ablaze pallets and piles of uncollected rubbish, prompting firefighters to intervene, AFP correspondents said.

Interior Minister Gerald Darmanin said that across France, 149 members of the security forces had been injured and at least 172 people arrested, including 72 in Paris.

Around 140 fires were set alight in Paris, said Darmanin, blaming "thugs" for the violence, who had come to Paris "to have a go at the cops and public buildings".

Some 1.089 million protesters took part in demonstrations across France, the interior ministry said, putting the Paris turnout at 119,000, the highest for the capital since the movement started in January.

The nationwide figure still fell short of the 1.28 million people who marched on March 7, according to the government figures.

Unions claimed a record 3.5 million people had protested across France, and 800,000 in the capital.

- 'Until the end' -

In Paris, several hundred black-clad radical demonstrators were breaking windows of banks, shops and fast-food outlets, and destroying street furniture, AFP journalists witnessed.

In the northeastern city of Lille, the local police chief Thierry Courtecuisse was lightly injured by a stone.

In Paris, a video went viral of a police officer in helmet and body armour being knocked unconscious and plunging to the ground after being hit on the head by a stone.

The garbage that has accumulated in the streets due to strikes by refuse collectors proved an appealing target, protesters setting fire to the trash piled up in the city centre.

"It is a right to demonstrate and make your disagreements known," Prime Minister Elisabeth Borne said on Twitter, but added: "The violence and destruction that we have seen today are unacceptable."

Unions again appealed for peaceful protests. "We need to keep public opinion on side until the end," said Laurent Berger, leader of the moderate CFDT.

Protesters briefly occupied the tracks at the Gare de Lyon train station in Paris, and some blocked access to Charles de Gaulle airport.

Anger surged after a defiant Macron said on Wednesday he was prepared to accept unpopularity over the pensions reform which he said was "necessary".

Even before then, a survey on Sunday showed Macron's personal approval rating at just 28 percent, its lowest since the anti-government "Yellow Vest" protest movement in 2018-2019.

- 'Excessive force' -

Acting on Macron's instructions, Borne last week invoked an article in the constitution to adopt the reform without a parliamentary vote. That sparked two no-confidence motions in parliament, which she survived -- but one by a narrow margin.

Thursday's protests were the latest in a string of nationwide stoppages that began in mid-January against the pension changes.

The ministry of energy transition on Thursday warned that kerosene supply to the capital and its airports was becoming "critical" as blockages at oil refineries continued.

Since the government imposed the reform last Thursday, nightly demonstrations have taken place across France, with young people coordinating their actions on encrypted messaging services.

There have been hundreds of arrests and accusations of heavy-handed tactics by police.

Amnesty International has expressed alarm "about the widespread use of excessive force and arbitrary arrests reported in several media outlets".

King Charles is due to arrive Sunday, with a trip scheduled on the new strike date of Tuesday to Bordeaux.

The fire at the entrance to the city hall in Bordeaux damaged its massive wooden door and was put out after 15 minutes, mayor Pierre Hurmic said.

French public sector trade unionists have warned they will not provide red carpets during the visit, but non-striking workers are expected to roll them out.