Tens of thousands of people took part in protests in central Paris and Rome organised by hard-left parties against government economic reform plans and austerity measures.
The protest in Rome turned violent on Saturday when a splinter group, many wearing masks and helmets, threw rocks, eggs, firecrackers and oranges at riot police at the industry ministry.
Riot police with batons charged the group, with protesters fighting back with rocks and firecrackers. One man lost a hand when a firecracker exploded.
In Paris, protesters marched with banners attacking President Francois Hollande with slogans such as "Hollande, that's enough" and "When you are leftist you support employees".
Police said that about 25,000 joined the protest, which came after Prime Minister Manuel Valls unveiled planned tax and spending cuts on Tuesday, vowing to bring down France's public deficit , following on from pro-business reforms announced earlier this year by Hollande.
The turnout, however, was well short of crowds in Paris last year against same-sex marriage that drew hundreds of thousands. The French Communist Party estimated Saturday's turnout at 100,000.
The protest in Rome was smaller, drawing several thousand, according to witnesses. They called for more affordable housing and took aim at Prime Minister Matteo Renzi and his plans to reform labour rules to make it easier for companies to hire and fire employees.
"The problem with the Renzi government is that since it took power, even though he is supposedly of the left his policies are of the right," said Federico Bicerni, a graduate from Modena with a temporary work contract who is also the youth head of the Italian Marxist Leninist Party.
"They are reducing democracy. Renzi's labour reforms will worsen the situation for workers without job security, hitting young people when they are already struggling. The rage of the people in the squares today is justified," he said.
Renzi, who took power in February, wants sweeping reforms, including tax cuts, to revive Italy's ailing economy where youth unemployment has risen to well over 40 per cent.
Hollande is struggling to turn around a weak French economy and hard-left parties have urged him to abandon his business-friendly reforms and public-sector deficit targets set by the European Union. They say the government's plans are hurting growth and are not helping bring down unemployment, which is above 10 per cent.
Hollande announced a "responsibility pact" earlier this year, which aims to boost the profitability of companies by cutting what they pay in social charges by €30 billion (HK$321 billion).
Polls suggest that the ruling Socialist party will finish third in next month's European elections, behind the conservative UMP and the National Front.
Paris is under EU disciplinary action for running too high a budget gap and already has been granted a two-year delay to reduce it to within the EU limit of 3 per cent of GDP by next year.