The Colbert building affected is less than 500 metres from Marseille’s picturesque Old Port in one of the city’s poorer neighbourhoods, where drug-dealing hotspots have recently popped up.

“After months of concern and alarm, the dean… has taken the decision to close the building to students and staff as their security cannot be assured,” Eric Berton, president of the Aix-Marseille University, wrote to police, prosecutors and the mayor.

Around 40 people have been killed in drug-related violence in Marseille this year — described as a “bloodbath” by city authorities  – including bystanders and local residents caught up in attacks on rival dealers.

Classes for the Colbert site’s roughly 1,500 students will take place online from Friday until October 13, Berton said, with a university source telling AFP the institution hopes the problems can be resolved by then.

The university “has a real desire to stay in the heart of Marseille” rather than fleeing its social issues, the source added.

Marseille’s police headquarters on Tuesday acknowledged the “degradation” around the Colbert site, but added it had been sending riot police to reinforce local officers.

It also invited university chief Berton to visit “soon” to discuss the dealing problems.