Hundreds of thousands of workers and students took to the streets of French cities on Thursday, braving heavy rain to protest against proposed labour changes.

The demonstrations - which led to scores of arrests as youths and police clashed in a number of cities - were part of a nationwide strike against changes that could alter France's 35-hour working week and make it easier to hire and fire employees.

Official figures said 390,000 people took part in the protests, while unions put the figure at 1.2 million.

Al Jazeera's Jacky Rowland, reporting from Paris, said up to 200 demonstrations took place across the country amid a number of strikes affecting public hospitals, transport and schools.

"It's not just the demonstrating but also the strikes indicating that workers, the unemployed, students and high-school students are all opposed to anything that will change the kind of working conditions and the kind of labour laws that France has known for decades," Rowland said.

Employees, workers and students took part in the nationwide protests [Claude Paris/The Associated Press]

'Shocking changes'

The protests, the fourth in a month, add further pressure to the Socialist government of President Francois Hollande, who has been plagued by low popularity and a jobless rate of more than 10 percent.

Hollande, who dropped a plan on Wednesday to strip those convicted of "terrorism" of French nationality, has previously said he will not run for re-election if he fails to reduce the country's number of unemployed.

Supporters of the labour changes say they will help France's economy and make the country more competitive, while critics believe workers will end up having fewer rights.

"It's shocking that a Socialist government introduced this law," Paris protester Zoe Farre, 23, told the Associated Press.

About 28,000 people marched in Paris' streets, according to the police.

Youth clash with riot police in Paris during Thursday's protest [Thibault Camus/The Associated Press]

Violent clashes

Earlier in the day, a few dozen protesters, mostly hooded or wearing masks, broke away from a peaceful student demonstration in eastern Paris to hurl paint bombs at banks and stores. Some smashed cash machines with bats or set off smoke canisters while confronting police.

Clashes also broke out between a small group of young protesters and the police in the cities of Nantes, Rennes and Toulouse.

Police arrested more than 100 people and at least 13 officers were injured, the interior ministry said.

The government proposal technically maintains that the 35-hour working week, but allows companies to organise alternative working times.

Those include a working week of up to 48 hours and 12-hour days. In "exceptional circumstances", employees could work up to 60 hours a week.

The bill is to be debated in parliament in April.

Unions said they planned further rallies on April 5 and 9 and the hardline CGT union said the protests would not end until the draft labour bill was withdrawn entirely.

Protests in France against proposed labour reforms

Source: Al Jazeera and agencies