In a statement the City Hall said it had initiated proceedings “that will result in €600,000 (£500,000) fines for each of them for the repeat offence of advertising tourist lodgings online” without authorisation on Thursday.
Under a 2012 regional law, any lodging rented to visitors in Catalonia must be recorded in the province’s Tourism Registry and have a permit.
The city council said it had found 3,812 lodgings on Airbnb and 1,744 on HomeAway that did not have permits, AFP reports.
The council is led by Ada Colau, a former spokeswoman for Spain’s anti-eviction movement, who is aiming to quell the vast number of visitors to the city over fears it could drive out poorer residents.
"It's not acceptable that there are thousands of flats operating illegally without a permit, without paying taxes and causing problems for the neighbours," she told Spanish radio on Thursday.
It comes after Barcelona authorities, gave both companies a €30,000 (£25,000) fine in December last year for advertising lodgings without permits.
At the time, this was the maximum fine for the offence, however in June the City Hall increased this to €600,000 (£500,000). This is the first time the city authorities have applied the new maximum fine.
Urban planning councillor Janet Sanz said the increase of the maximum fine came after the two sites continued to advertise properties without permits.
"This illegal offer has a very hard impact on our neighbourhoods, it raises rental prices, fuels the underground economy and generates conflicts between neighbours," she told a news conference, the Local reports.
"The municipal government will introduce changes in the penalties that are applied. We want to reach maximum fines of up to €600,000."
Airbnb, based in San Francisco, claims it provides a useful service by helping visitors find affordable temporary lodging while enabling homeowners to supplement their income.
Andreu Castellano, a spokesperson for the company, said it was “saddened” by the decision and would appeal.
“Less than a month ago, we met with officials and Airbnb committed to work together in the best interest of the city,” he added.
“Airbnb is part of the solution in Barcelona. We want to be good partners to cities and we will keep proactively seeking collaboration with Barcelona to maintain this dialogue and support regular people who share their homes.”
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