Riot police in Argentina’s capital Buenos Aires fired tear gas and water cannon to disperse protesters outside Congress, before lawmakers gave an initial approval to budget-slashing reforms in Brazil’s Senate on Wednesday.

Demonstrators – who say the measures will hurt millions of Argentines – threw petrol bombs and stones, setting one car alight.

A number of people were reported injured, with local media describing the scene on Wednesday as a “battlefield”.

The reform package, proposed by right-wing President Javier Milei to revive the country’s flagging economy, includes declaring a state of economic emergency, cutting pensions and watering down labour rights.

The measures are opposed by leftist political parties, labour unions and social organisations.

But the motion, which was initially tied 36-36 in the Senate, was preliminarily passed on Wednesday after the head of the chamber, Vice President Victoria Villarruel, broke the tie.

“For those Argentines who suffer, who wait, who do not want to see their children leave the country… my vote is affirmative,” vice president and Senate leader Ms Villaruel said after breaking the tie.

The 328-article bill will now be surveyed point by point before it’s expected full approval on Thursday.

It will then return to the lower house for the final go ahead.

Ahead of the bill’s passing in the Senate, protesters chanted: “The country is not for sale, the country is defended,” while one banner read: “how can a head of state hate the state?”

Scuffles broke out earlier in the day when protesters tried to make their way towards Congress through fences, with demonstrators throwing rocks at officers who pepper sprayed them.

Observers and opposition MPs said dozens of demonstrators and a handful of MPs received medical attention. At least five opposition MPs in the crowd were hospitalised, legislator Cecilia Moreau told AFP news agency.

At least 20 police officers were also injured, officials said. Security forces said they arrested 15 people.

Police later pushed back protesters, who reportedly set two vehicles on fire – including that of a news organisation.

“We cannot believe that in Argentina we are discussing a law that will put us back 100 years,” Fabio Nunez, a 55-year-old protesting lawyer, was quoted by AFP as saying.

President Milei’s office issued a statement thanking the security forces for repressing what it described as “terrorists” attempting to carry out a coup d’état.

“We are going to change Argentina, we are going to make it the most liberal country in the world,” Mr Milei told a conference in Buenos Aires.

The highly-divisive bill was approved by the lower house in April, after significant amendments were made to it.

Mr Milei came to office in 2023 after vowing to take a chainsaw to public spending.

While on the campaign trail, he even brandished a chainsaw while making a speech to symbolise his determination to do so.

He has since cut the cabinet in half, slashed 50,000 public jobs, suspended new public works contracts and ripped away fuel and transport subsidies even as annual inflation approached 300%.