London Mayor Sadiq Khan has written to six short-term lets websites calling on them to introduce a 90-day limit on rentals in the capital.

Last December, Airbnb announced that it would block London landlords from letting their properties for more than 90 days a year without planning permission.

The move was widely welcomed by the property industry and the Mayor’s office has publicly praised it as a ‘forward-thinking’ initiative.

Now Khan has written to six other websites – Veeve, One Fine Stay, Wimdu, Booking.com, HomeAway and Airsorted – urging them to take action.

The Mayor says that letting properties on a short-term basis all year round could lead to a loss of much needed rental housing stock in London.

However, he concedes that Londoners benefit from short-term lets and that the success of platforms like Airbnb is another indication that the capital is ‘open’ for business.

Khan has explained to the six websites that self-regulation can offer an alternative to calls for government intervention into the burgeoning short-term lets industry.

An excerpt of the Mayor’s letter reads as follows:

“While Airbnb accounts for a substantial share of the short-term lettings market in London, there are many other operators, such as yours, who occupy the same space. I am keen to see a cross-industry response to this issue, to help local authorities enforce the law.

“I therefore strongly encourage your company to follow Airbnb’s lead, by ensuring that customers of yours who want to let properties in London on a short-term basis for more than the 90-day annual cumulative limit are restricted from doing so through your website, unless they can prove that they have the relevant planning permission.”

Analysis by AllTheRooms suggests that Airbnb’s 90-day limit in London could cost the platform in excess of £325 million a year.

Meanwhile, a recent BBC investigation revealed that a third of London councils don’t believe the 90-day limit will work.

London Assembly member Tom Copley says local councils ‘don’t have the resources’ to enforce the 90-day rule and so it is up to providers to ‘step in’.

“It’s hugely welcome that Airbnb have stuck their heads above the parapet. We need others in the industry to now follow suit,” he says.