SPAIN’S idyllic beaches, bold architecture, vibrant night-life and colourful culture draws millions of tourists every year. But behind the paradise a hostile battle is bubbling to the surface.

And we are at the centre of it.

Many Spaniards are growing frustrated by armies of tourists taking over town centres, disrupting the lives of locals and putting a strain on resources.

In 2016, some 75.3 million people visited the European country. That grossly outnumbers the country’s actual residents, of which there are about 46 million.

In fact, Spain has broken its own tourist number records each year for the past four years and currently holds the title of the world’s third most popular tourist destination, according to the UN’s World Tourism Organisation.

And while tourism represents some 11 per cent of Spain’s 1.2 trillion euro ($1.8 trillion) gross domestic product, an anti-tourism movement has been simmering among locals for quite some time. But it appears the anger may now be close to boiling point, with frustration turning into actual violence.

Last week there was a troubling assault on an open-top tourist bus in one of Spain’s most popular tourist destinations, Barcelona, as it pulled up outside the Camp Nou stadium of the city’s iconic football team FC Barcelona.

Four masked assailants slashed the vehicle’s tyres and scrawled “El Turisme Mata Els Barris” in Catalan — which translates as “Tourism Kills Neighbourhoods” — onto the bus windscreen.

At the time, many of the visitors on board that bus feared they were actually caught in a terrorist attack rather than what turned out to be an anti-tourist protest.

“I really thought it was a terrorist attack and my number was up,” British visitor Andrew Carey of Bridgend, who was on the bus with his wife Natalie, told the Telegraph.

“Masked men surrounded the bus and began shouting. We were getting ready for someone to come up the stairs with a knife or a gun. It was a relief that they just sprayed graffiti.

“It was very frightening.”

And just days later the tyres of rental bicycles for tourists were slashed.

Arran, the youth wing of the radical pro-independence political party CUP (Popular Unity Candidacy), has claimed responsibility for the anti-tourism campaign. They consider themselves activists fighting the rise of mass tourism in Spain.

At the core of the group’s problem with mass tourism is the belief that it creates an economic divide for the working classes, who are unable to afford apartment rentals because they are being forced out of the market by holiday-makers and inflated prices.

Accompanying a video of the Barcelona bicycle slashing that the group posted on Twitter, they wrote: “We are fed up with the occupation by tourist companies of the public space of the neighbourhood.” The account is littered with other similar anti-tourism sentiments.

Ja n'estem fartes de l'ocupació per part d'empreses turístiques de l'espai públic del barri, ACTUEM!

UNEIX-TE AL COMBAT✊🏼 pic.twitter.com/PG7Ru3xljY — Arran del Poblenou🗝 (@ArranP9) July 31, 2017

A spokesman for Arran said the vandalism in Barcelona was an act of “self defence”.

“The mass tourism in Catalonia is generating huge social inequality,” a spokesman told IBTimes UK.

“Thousands of people are forced to leave their neighbourhoods and thousands more are forced into very bad working conditions.”

It is estimated that Barcelona pulls in around 32 million visitors a year, including cruise passengers and day-trippers. That’s 20 times the city’s population of just 1.6 million.

And Arran aren’t the only ones fighting against it in Barcelona. The anti-tourist movement gained momentum when in June 2015, the city got a new mayor, Ada Colau — an outspoken critic of tourists.

After being elected to office, Colau, who is a member of the Barcelona in Common party, said she feared Barcelona would “end up like Venice”, a city in which tourism has been blamed for driving locals away.

She then introduced tourist caps, including on the city’s famous La Boqueria markets, and put a one-year moratorium on new licences for hotel and tourist apartments in the city.

And Barcelona also isn’t the only Spanish city in the fight either. Arran has fought back in the Spanish island of Majorca.

Members of the group recently stormed a restaurant in Palma, a resort city and the capital of Majorca.

They threw confetti and set off smoke bombs at a the Mar de Nudos restaurant, and displayed a poster which read: “Tourism Kills Majorca”, according to The Times.

Last year, Palma was also branded with unwelcoming messages to incoming tourists. On an old brick wall in a town centre, the words “Tourist go home” were emblazoned in bright red spray-paint. Another message on another wall, this one in black, read: “Tourist you are the terrorist”.

Ibiza and Minorca, which make up the Spanish Balearic Islands with Majorca, have also expressed concerns over a rising number of visitors.

In the popular party island of Ibiza, which is prone to drought, water reserves are dwindling. In rural Menorca there are fears natural attractions could be ruined by tourism.

To try and combat the problems mass tourism can bring, the Balearic Islands implemented a Sustainable Tourism Tax in July 2016 — an additional payment of up to two euros ($AU3) for each overnight stay.

Back in Barcelona, Colau condemned the attack on the tour bus by tweeting that “protesting against tourism can never be about intimidating people or damaging facilities”.

But Laura Flores, a spokesman for Arran, said that the group’s vandalism is “a response to the violence we face every day. The street must be allowed to speak; it’s the only place where we can fight,” she said, according to The Guardian.

Read more: Barcelona terror attack sees at least 13 people killed at iconic Las Ramblas tourist hotspot in Spain