Concerns have been raised at government level over the illegal use of Airbnb by private landlords.

Airbnb is meant to be for short lets of no more than 90 days in a year, but a number of landlords are using the site to advertise much longer lets. Assured Shorthold Tenancies, generally for six or 12 months, carry with them legal obligations.

Landlords who use Airbnb to advertise lengthy tenancies are breaching regulations that apply to lets of more than 90 days.

Those who do so break both normal AST and other legal requirements, are risking prosecution and running into difficulties when it comes to claiming back their properties. They are also bypassing agents able to give them the appropriate advice.

However, influential Labour MP Iain Wright has said that the current law may be unenforceable.

Wright, chair of the Business, Innovation & Skills Committee, and a former junior housing minister, has written to London mayor Sadiq Khan about his concerns.

Wright’s letter says: “You will be aware that a number of investigations into temporary property letting companies such as Airbnb have found that many landlords appear to be operating illegally by letting properties out for more than 90 days per year. Several of these report that the current law is unenforceable.

“During my Committee’s recent inquiry into the Digital Economy, we heard evidence that while companies such as Airbnb can enable home owners to unlock economic value by temporarily letting spare rooms, extensive use of Airbnb by professional landlords, contrary to the current law, can help to drive up property prices, compounding issues of affordability in the capital.

“Organisations such as the British Hospitality Association have also expressed concern that companies such as Airbnb enable landlords to circumvent tax, food, health and fire safety regulations thereby securing an unfair competitive advantage over other providers of accommodation.

“Although I understand that enforcement of the 90-day rule is the responsibility of individual London councils, I would welcome your own assessment of the impact of companies such as Airbnb on London and your views on whether the existing law should be amended.

“I am also keen to understand what discussions you have had with representatives of London councils on enforcement of the 90-day rule.

“I am copying this letter to Cllr Claire Kobler, the chair of the London Councils umbrella body, the British Hospitality Association and Airbnb.”

The Residential Landlords Association has raised repeated concerns about the number of lets advertised on Airbnb which are for longer than 90 days, and in many cases for considerably longer.