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The accommodation website Airbnb has delisted a number of its UK hosts in recent weeks but given no explanation to property owners.

Many of the hosts that the BBC has spoken to have had no negative reviews and the owners are unable to appeal.

It is not clear how many of Airbnb's 52,000 UK-based hosts have been delisted, but it could be in the hundreds.

Airbnb said: "We routinely carry out initiatives for quality purposes."

Its answer was insufficient for William, who owns a townhouse built in 1730 in Soho, in London's West End.

He has been renting out a flat at the top of the house through Airbnb since 2013 - until he was told two weeks ago that the property would be delisted.

"We found it a bit insulting," William said. "We really try to arrange the flat to give people a good experience. We provide fresh flowers and breakfast for guests. We take a lot of trouble and we've had uniformly positive reviews over three years."

Image caption William offered a Soho flat on Airbnb until it was abruptly delisted in January

He received an email from Airbnb on 27 January that said:

"Unfortunately, our systems have shown that the listing mentioned below is not delivering the kind of local hospitality experience guests are looking for.

In line with our Terms of Service, '2-bed Flat in Historic Soho House and 1-bed flat in 1730s Soho house' will be removed from our platform on 9 February 2016.

Please understand that this determination was not made due to a single attribute, but an overall combination of various criteria."

For others, the removal was just as sudden but will have a far greater impact.

Guneep Luther had 14 of his 17 properties on Airbnb delisted with just two weeks' notice.

His rental income of up to £45,000 a year was mostly dependent on the California-based company, which is registered for tax in Ireland.

'In the dark'

"Initially I had nothing but praise for Airbnb. The website is incredibly easy to use, customer service were very friendly and replied to any questions instantly," Mr Luther said.

"Now, I feel as if Airbnb has completely ruined my business. They have not only left me in the dark, I have many bills to pay for all properties and I employ two cleaners and I am very concerned about their future.

Airbnb are not being transparent in what ever is going on inside the company and I feel this is not fair on hosts or guests as many guests are worried about their bookings."

And some Airbnb forums have been dotted with hosts who have also been suddenly delisted without any clear reasons being given.

But Airbnb says the entire customer experience is central to the success of its offering. Positive reviews lead to more guests trying out the service. Negative reviews damage the host, the company and the informal "sharing economy" that the travel app Uber has also made famous.

When contacted by the BBC, the company said: "Our mission is to allow Airbnb guests to connect with hosts who provide local and authentic experiences that make cities better places to live, work and visit. We routinely carry out initiatives for quality purposes and adherence to this mission...

"As said previously, this is not unusual or unique. It's routine activity that happens around the world. "

Possible flotation

Airbnb was established in 2008 in San Francisco when its founders offered air mattresses as an alternative to hotels and guesthouses to conference attendees in Silicon Valley.

Image caption Paul Maher believes Airbnb may be taking action ahead of new regulations

Now it is worth an estimated $25bn and may be about to float on the stock exchange. If it does list, investors may wish to see the technology giant be stricter on all sources of revenue in future.

"It has unfortunate consequences for people who've been de-listed and there is an opportunity cost of re-advertising a property," according to Paul Maher from Positive Marketing.

"But we have to remember that although it's called the 'sharing economy', it is a business after all. And for any reason if the business decides to delist you, that's their prerogative."

New regulations

Airbnb provides a platform for anyone with spare space, houses, chalets and even castles to rent out for a day at a time. The company does not inspect each property but offers a free photography service to hosts.

Guests and hosts both pay separate commissions to Airbnb, on top of the rental fee, and all the money is retained by the company until the guest arrives at the property.

Mr Maher believed that these delistings may be Airbnb trying to get ahead of the game before new regulatory restrictions come into force, including taxes similar to those payable by hotels and guesthouses.

"Slowly the sharing economy is having some of the problems that traditional business faced. It may be that they are getting very vigorous about revenue streams. And if that involves de-listing some people, that's the consequence," he said.