Argentine police fired tear gas and used water cannon on Wednesday to disperse demonstrators, who threw rocks and firebombs outside Congress during a debate over labor reforms opposed by trade unions.

Thousands were protesting a bill that would make employment contracts more flexible, restrict the right to strike and make it cheaper to fire workers.

Libertarian President Javier Milei argues that Argentine's current labor laws are too restrictive and dissuade employers from on-the-books hiring. 

Almost 40 percent of Argentine workers lack formal employment contracts.

But unions say the reforms erode workers' rights.

A group of protesters broke away from the main demonstration, which was peaceful, to throw rocks and other projectiles at police guarding Congress in central Buenos Aires.

The police responded with copious amounts of tear gas.

The bill, which Milei wants to fast-track through parliament, is the latest in a program of reforms pushed by the self-described anarcho-capitalist president.

Since taking office in December 2023, Milei has also slashed government employment, cutting tens of thousands of jobs.

The labor reform bill reduces severance pay, allows payments in kind and restricts usage of vacation time, among other proposals that the General Confederation of Labor (CGT) considers "regressive."

The Senate is expected to vote later Wednesday on the bill, after which it will be put to the lower Chamber of Deputies.