French trade unions on Friday issued an ultimatum and threatened the new Prime Minister Sebastien Lecornu with new strikes after a day of mobilization against the controversial budget proposals.

"The ball is now in the Prime Minister’s court. If he does not respond to their demands by September 24, the trade union organizations will meet to quickly decide on a new day of strikes and demonstrations," a joint statement issued by the CGT trade union said.

Welcoming the "success" of the Sept. 18 mobilization, unions underscored that it was "not enough."

They demanded the complete withdrawal of the entire budget project, fiscal justice, adequate budgetary resources for public services, high-level social protection and the abandonment of plans to raise the legal retirement age to 64.

They also demanded social and environmental conditionality for the €211 billion ($247 billion) in public aid to private companies, alongside investments in a just ecological transition, the reindustrialization of France, and measures to prevent layoffs.

"The success of September 18 puts workers in a position of strength. The trade union organizations have already agreed to meet regularly to take all necessary initiatives to put the budget debate under pressure from the working world and finally achieve social justice," the statement added.

Unions claim that more than 1 million people took part in Thursday’s nationwide protests, while the Interior Ministry estimates the number at around 500,000.

Authorities reported that 309 people were arrested, including 134 taken into custody, while 26 members of the security forces were injured.

Organized by major French trade unions, the mobilization came in response to controversial budget proposals introduced by former Prime Minister Francois Bayrou.

The Sept. 18 action followed the “Block Everything” mobilization last week, which drew nearly 197,000 people nationwide.

- Controversial national budget plan

France is facing mounting political tensions as Bayrou lost a confidence vote in the National Assembly on Sept. 8.

Bayrou, who unveiled a 2026 budget framework in July, was seeking support for a plan to save nearly €44 billion ($51 billion) as part of efforts to reduce France’s soaring public debt, now at 113% of its GDP.

French President Emmanuel Macron appointed Armed Forces Minister Sebastien Lecornu as the country’s new prime minister. He has been tasked with holding consultations with political parties before forming his government.

France has one of the EU's largest budget deficits at 5.8% of GDP.

Budget negotiations have been a major source of tension in French politics.

The failure to reach an agreement on the 2025 budget last year also led to the collapse of the Michel Barnier government in December after left-wing and far-right parties united behind a no-confidence motion.