Forza Nuova website taken offline after No Green Pass protest violence in Rome.

Italy's postal police have blocked the website of the neo-fascist Forza Nuova group after its leaders were arrested for their role in a violent protest in Rome against the government's covid Green Pass.

The move follows a request from the Rome Public Prosecutor's Office as part of a probe into the clashes that broke out in the centre of the capital on Saturday night, including the storming of the CGIL trade union headquarters and the casualty ward of the Umberto I hospital.

• Calls in Italy to ban Forza Nuova after Rome 'Green Pass' violence

The violence led to the arrests of 12 people, including Roberto Fiore and Giuliano Castellino, the national leader and Rome leader of Forza Nuova respectively; and the leader of the IoApro movement, the Modena-based restaurateur Biagio Passaro who filmed the CGIL assault on Facebook Live.

• Rome protest over Italy's covid Green Pass turns violent

The Rome prosecutor's office says there was a "concrete and current danger" that "the free availability and visibility of the site could aggravate and prolong the consequences of the alleged offence, continuing to publicise 'fight and clash' methods of protest, based on violence and on prevarication."

The news comes amid growing calls from left and centrist parties in Italy for Forza Nuova and other pro-fascist groups to be dissolved.

• Italy PM visits Rome trade union base stormed in Green Pass protest

CGIL is among the trade unions organising a major anti-fascist rally in defence of "work and democracy" in Rome on Saturday 16 October.

The event will be held on the eve of a run-off mayoral vote, as the centre-right Enrico Michetti and the centre-left Roberto Gualtieri (PD) battle to succeed Virginia Raggi as the capital's new mayor.

• Green Pass: How to get Italy's digital covid cert and how it works

Saturday night's demonstration in Rome was held in protest over an imminent requirement for all workers in Italy to have the Green Pass - a digital or paper certificate showing that people have been vaccinated, tested negative or recovered from covid-19.

The move, set to affect 23 million workers, will come into force on 15 October and will remain in place until 31 December when Italy's covid state of emergency legislation expires.

Details about the Green Pass can be found - in Italian - on the Certificazione Verde website while for official information about the covid-19 situation in Italy - in English - see the health ministry website.