Revellers left an illegal New Year rave in northwestern France that had drawn some 2,500 people, led to clashes with police and sparked concerns it could spread the coronavirus.

Police had failed to stop the underground event, set up on Thursday in two disused warehouses in Lieuron, south of the city of Rennes in Brittany.

Such mass gatherings are banned across France to prevent the spread of Covid-19, and a nationwide 8pm curfew — which was not lifted for New Year — applies across the country.

Techno music had blared out during the night from the warehouses, which had been transformed into illegal nightclubs for partygoers who had flocked to the site from across France and even abroad, AFP reported.

The local prefecture said the music had been switched off and sound systems dismantled after two nights, and the first revellers began leaving the site before dawn.