Rome’s famous fountain has had to be drained of 300,000 litres of water following a dramatic demonstration by anti fossil fuel campaigners.

This Sunday visitors to the Trevi Fountain, Italy’s most recognisable wishing well, were shocked to see the waters turn deep black, stained by dark ink.

Up to eight demonstrators were seen wading into the fountain carrying orange signs.

The protestors from the Italian activist group Ultima Generazione (“Last Generation”) took to the monument to ask the government to stop public subsidies for fossil fuels.

The group were quickly stopped by police but not before hundreds of thousands of litres of water were dyed black with charcoal and vegetable inks.

Tourists and onlookers were mixed in their reception, meeting the action with applause and jeers.

Protesters in Italy turned the Trevi Fountain’s water black this weekend. Photo / Last Generation; Alessandro Penso

On Monday however, the Mayor of Rome’s office was less ambiguous about the stunt.

Mayor Roberto Gualtieri blamed the group for wasting city funds and threatening its cultural landmarks.

 “Thanks to the timely intervention of the local police, the worst was avoided. An intervention is now needed that will commit public resources and lead to the waste of 300,000 litres of water,” tweeted the civic leader.

“This is not the right way to conduct a battle for the environment and against climate change.”

There appeared to be no damage to the white marble fountain.

The group updated their website and social media with images of the stunt, asking for donations for their cause and to cover the legal costs of their direct actions.

“According to the prosecutor’s office, we are a criminal association,” said the group’s crowdfunding page which disputed the title of “ecovandali” or “eco-vandals”.

The Trevi fountain draws 10.5 million visitors every year and is arguably one of Europe’s most famous landmarks. Tourists are regularly fined for swimming in the waters, which carries a €450 ($735) penalty.

The group’s actions came as Italian prime minister Giorgia Meloni visited the Emilia Romagna region which had been affected by the worst floods in a century.

The PM cut short attendance of the G7 summit in Japan to see the flood-stricken region, which scientific advisors said had been suffering from climate change.