Riot police in Argentina's capital Buenos Aires have fired tear gas and water cannons to disperse protesters outside Congress, where lawmakers have been debating budget-slashing reforms.

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.

"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 as saying by the AFP news agency.

When Mr Milei was campaigning last year to lead the South American nation, he brandished a chainsaw to symbolise his determination to radically cut public spending and hyperinflation.