Violent protests against pensions reform in France led to the postponement Friday of King Charles III's trip to the country, highlighting the growing security and political problems faced by President Emmanuel Macron.
The French president condemned the latest burst of violence overnight, while the Council of Europe criticised the "excessive use of force" by some police officers during recent demonstrations.
King Charles' first foreign trip as monarch had been intended to highlight warming Franco-British relations. Instead, it has underlined the severity of demonstrations engulfing Britain's neighbour.
Macron asked for the postponement during talks on Friday morning, a UK government spokesperson said, with the change blamed on a call for fresh strikes next Tuesday on the second day of the king's tour.
The decision was made "to welcome His Majesty King Charles III in conditions which reflect our friendly relations", Macron's office said.
Police arrested more than 450 people on Thursday, according to interior ministry figures. In addition, 441 members of the security forces were injured on the most violent day of protests since the start of the year against Macron's bid to raise the retirement age from 62 to 64.
More than 900 fires were lit around Paris, with radical anarchist groups blamed for setting uncollected rubbish ablaze and smashing shop windows, leading to frequent clashes with riot police.
But rights groups, magistrates and left-wing politicians have also denounced alleged police brutality in recent days.
And the Council of Europe -- the continent's leading human rights watchdog -- warned that sporadic acts of violence "cannot justify excessive use of force by agents of the state" or "deprive peaceful protesters of their right to freedom of assembly".
In the northeast city of Rennes, regional officials denied claims by union leaders that police had deliberately targeted them with tear gas and a water cannon during Thursday's protests in a bid to intimidate them.
In Bordeaux, protesters set fire to the ancient wooden entrance to the city hall on Thursday. King Charles had been set to visit the southwestern city on Tuesday, after a day in Paris.
Some observers feel the cancellation would avoid further embarrassment for France, with protesters threatening to disrupt the royal visit and the streets of the capital strewn with rubbish because of a strike by waste collectors.
The second leg of Charles' European tour -- to Germany -- is expected to proceed as scheduled on Wednesday.
More than a million people marched in France on Thursday, the protest movement reinvigorated by Macron's tactics and statements over the last week.
Uproar over the legislation to change the retirement age -- which Macron pushed through parliament without a vote last week -- has created another huge domestic crisis for the president just 10 months into his second term in office.
"I condemn the violence and offer my full support to the security forces who worked in an exemplary manner," Macron told reporters Friday during a trip to Brussels.
Macron's decision to force the legislation through parliament and his refusal to back down in a television interview on Wednesday appeared to have energised many opponents on Thursday.
Commentators are questioning how the crisis will end, just four years after the "Yellow Vest" anti-government demonstrations rocked the country.
"No one knows where the way out lies," political scientist Bastien Francois from the Sorbonne University in Paris told AFP.
"Everything depends on one man who is a prisoner of the political situation."
The leader of the moderate CFDT union, Laurent Berger, said Friday he had spoken to an aide to the president and suggested a pause on implementing the pensions law for six months.
"It's the moment to say 'listen, let's put things on pause, let's wait six months'," Berger told RTL radio. "It would calm things down."
Blockades of oil refineries by striking workers continued on Friday, but the energy transition ministry said it had requisitioned enough workers to restart production at one of these, and resume fuel supply to the capital.
Some flights have been cancelled until at least Wednesday at airports around the country due to a strike by air traffic controllers.
Police and protesters will face off again Saturday, and not just at demonstrations over the pensions reform.
At Saint Solines, central France, thousands of people are expected at a protest against the deployment of new water-storage infrastructure for agricultural irrigation, despite an official ban on the gathering.