French police stepped in to halt skirmishes between British soccer fans and locals in the port city of Marseille overnight, just hours before the Euro 2016 championship opens in France.

A police official said two British fans had been injured and four police officers slightly hurt in a string of incidents in the southern French city, due to host an England-Russia match tomorrow.

Paris, in contrast, hosted a massive music concert near the Eiffel Tower where tens of thousands of revellers danced late into the night, with no immediate reports of major trouble ahead of the month-long tournament.

Paris Mayor Anne Hidalgo said nearly 90,000 people attended the festivities. "And it all went off beautifully."

The police official said the Marseille incidents involved about 100 Britons and 50 or so local residents.

Interior ministry spokesman Pierre-Henri Brandet said the overnight incidents amounted to a scuffle between fans that did not call security measures into question. Full-scale security would be deployed for Saturday's match in Marseille, he said.

The Euro championship was set to open later tonight with France facing Romania under tight security at the Stade de France stadium north of Paris.

Almost 90,000 police and security staff are being deployed at stadiums around the country that will host millions on fans in the coming weeks and at official fan zones where millions more will be able to watch matches on giant TV screens.

The event takes place nine months after Islamist militants killed 130 people and injured hundreds of others in multiple attacks on Paris and outside the stadium where Friday's night's match takes place.