The city of Paris on Monday threatened to take Airbnb to court if it does not delist hundreds of apartments whose owners have failed to register with the French capital's authorities.
Mayor Anne Hidalgo's deputy in charge of housing, Ian Brossat, told AFP the city had written to five holiday rental sites -- Airbnb, HomeAway, Paris Attitude, Sejourning and Windu -- to demand they remove properties whose owners have defied the city's new registration requirements.
If they do not comply the city will take legal action, he added.
Paris -- the world's third-most visited city, according to a Mastercard ranking -- is one of Airbnb's top markets, with some 65,000 homes listed.
Another 35,000 are available on rival platforms.
Faced with complaints that holiday rentals are increasing property speculation and pricing hoteliers out of the market, the city has slapped restrictions on short-term rentals of apartments and rooms.
Since December 1, anyone wanting to rent their home on an online platform must register it with the city and display a number on their ad.
The system allows French authorities to ensure the property is not being rented for more than 120 days a year -- the maximum duration for which a person can rent out their main residence.
So far, about 11,000 properties have been registered, representing only about a fifth of the total number of rental properties, Brossat said.
Paris officials have flagged up around 1,000 Airbnb ads that are in breach of the regulations and about a hundred each on the other four sites.
"The least they can do is respect the law," said Brossat, a member of the Communist Party and deputy to Socialist Mayor Anne Hidalgo.
Airbnb has come under heavy scrutiny in France, where tax authorities are tightening the noose around homeowners who fail to declare their rental income for tax purposes.
Earlier this month, the government summoned Airbnb's local managers to demand answers over a system allowing homeowners to be paid onto a prepaid credit card -- a mechanism suspected of facilitating tax avoidance.