Thousands of people marched in Rome on Saturday during the summit of the leaders of the Group of 20 major economies, calling on them to act against climate change and ensure fair access to Covid-19 vaccines.
Climate activists led the march, carrying colourful placards, playing drums and dancing as they demanded world leaders save the planet.
"We are holding this protest for environmental and social issues and against the G20, which continues undaunted on a path that has almost led us to social and ecological failure," said protester Edoardo Mentrasti.
They marched alongside students and groups of workers in a city on high security alert, with up to 6,000 police and about 500 soldiers deployed to maintain order. Metro stations have been closed and bus routes diverted due to the G20 summit.
Italian police are particularly anxious about unrest after recent protests over the country's mandatory Covidhealth pass for workers turned violent when neo-fascist activists attacked the headquarters of the CGIL labour union in Rome.
In Saturday's march, a large banner saying "stop patents, vaccines are a global right" was held by demonstrators parading along the banks of the Tiber river.
In the morning, the G20 leaders kicked off two days of talks where they were set to acknowledge the existential threat of climate change, but stop short of radical new commitments to tame global warming.
"There is an alternative to a development model based on 20 of the world's most important heads of state meeting in a room and deciding on the fate of the world," demonstrator Luca Ianniello said.
A separate, smaller protest against the Italian government, was in progress a few kilometres away.
Demonstrators have been kept far from the summit centre, located in a suburb built by the 20th Century fascist dictator Benito Mussolini.