Left-wing activists - branded “crazy extremists” by the prime minister - are taking part in demonstrations across the destination popular with Brits.
Revellers have hit headlines in recent weeks for boozy and violent behaviour at some of the country’s most popular resorts.
Today Rafael Gallego, chair of the Spanish Association of Travel Agents (Feaav), branded the protesters “fascists” and said he feared their actions will get worse.
SOLARPIXTHREATS: Anti-tourism protesters in Spain have targeted hotels and favourite holiday resorts
“Now there are protests in the entrances of hotels, restaurants and in ports”Rafael Gallego
Mr Gallego said: “This tourismphobia has been worrying us since last summer. In 2016 we noted graffiti and there was an aggression with a glass against tourists who were on an excursion, so we alerted that the situation could radicalise, which is what we have seen.
“Now there are protests in the entrances of hotels, restaurants and in ports.
“The danger is that tomorrow there could be an incident of real violence.
SOLARPIXVIOLENCE: Protesters set off smoke flares outside a seafront restaurant in Majorca
“They call themselves left-wing but they are more fascist than the far right. We are very worried that they might cause a serious incident with our visitors at any day.”
Mr Gallego defended the tourist industry, saying: “It is the sector which has recovered the greatest numbers of jobs since the crisis."
This summer four hooded activists from a radical group called Arran attacked a tourist bus in Barcelona, slashing tyres and spraying slogans across it. Others have thrown eggs at hotels, and there have been demonstrations around the city’s famous Sagrada Familia basilica.
SOLARPIXDEMOS: Left-wing groups are against tourism in Spain
In Palma, Majorca, they set off smoke flares outside a seafront restaurant, while in Bilbao, northern Spain, another group sprayed paint across the headquarters of the Basque Country tourist board yesterday/on Wednesday.
The groups claim tourism is destroying Spanish cities, driving up rent and forcing out young people.
On Tuesday PM Mariano Rajoy defended the tourism industry, which employs 2.5m people in Spain.
He called the activists “radical extremists” and said it was “crazy” to drive away tourists.
Today Mr Rajoy reiterated his support for the industry, saying it was “senseless madness” to attack tourism.
He added: “I never thought I would have to defend the Spanish tourism industry. It’s completely outrageous.”