Iran Press/ Europe: The protesters called on G20 leaders to act against climate change and ensure fair access to COVID-19 vaccines.
Climate activists led the march, carrying colourful placards and playing drums as they demanded world leaders save the planet, Reuters reported.
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 COVID health pass for workers turned violent when 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.
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 politician Benito Mussolini.
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