France, Jan. 29 -- Once shunned by well-heeled tourists, France's sprawling port city Marseille is attracting more and more visitors with its southern sunshine and cutting-edge culture. But as the city prepares for a bumper summer boosted by the 2024 Olympics, tension is reaching boiling point between landlords looking to profit from holiday lets and activists who say an Airbnb boom is squeezing the supply of affordable housing.

"Are there still real Marseille locals living here, or is it mostly Airbnbs?"

Lucile, a tourist visiting for the weekend, asks the question as she strolls through Le Panier, the city's oldest neighbourhood and now one of its most popular areas to stay.

Its meandering alleys, once known as a haven for criminals ...