Nice Mayor Christian Estrosi has urged Swiss fans not to travel to the city for Basel’s Europa Conference League quarterfinal second leg on April 20.

“I can only express my concern about the upcoming arrival of hundreds of Swiss fans in the streets of Nice,” Estrosi wrote on Twitter on Tuesday.

“It is out of the question to witness another outburst. I ask that Swiss fans do not make the trip.”

Basel fans were involved in a brawl in France last year when the Swiss team played Olympique de Marseille in the Conference League last 16.

Local police had to intervene when fans of both teams clashed using projectiles and fireworks hours before the match.

There were also disturbances in Nice in September when the start of the Conference League group match against Cologne was delayed due to crowd trouble at the Allianz Riviera stadium.

“I call on the State to take all necessary measures to put an end to the public disturbances that systematically accompany the travel of these supporters,” Estrosi added.

“I call on our national and sporting authorities to take the necessary decisions to ensure that this match takes place in the best possible conditions.”

Nice faces Basel in the first leg in Switzerland on Thursday.