The country's terror threat level has now been raised to 'severe'.
The terror threat level has been raised to four out of five.
The Foreign and Commonwealth Office (FCO) website says, “Terrorists are likely to try to carry out attacks in Spain.
“Attacks could be indiscriminate, including in places visited by foreigners.
“The Spanish authorities take measures to protect visitors, but you should be vigilant and follow the instructions of the local authorities.”
‘Intention to carry out attacks’
The FCO also explains that "Spanish police have disrupted a number of groups suspected of recruiting individuals to travel to Syria and Iraq from 2015 to the present date.
"Some of them expressed an intention to carry out attacks in Europe.
"There’s a heightened threat of terrorist attack globally against UK interests and British nationals from groups or individuals motivated by the conflict in Iraq and Syria. You should be vigilant at this time."
The Daily Star online reports that up to 40,000 more Spanish police will be deployed to tourist hotspots across the country - with police visible outside stations, beaches, hotels and restaurants.
The aim of the so-called ‘Operation Summer’ is to “take full action to obtain information in order to prevent terrorist acts” while also “reinforcing security measures at events and places that will attract a large number of people”.
The FCO explains that British nationals who are travelling or living overseas, particularly in areas where a crisis is more likely to occur, “should take sensible precautions.”
“This applies if you’re travelling to or living in a location where there is a high risk of terrorism, unrest or natural disasters,” adds the FCO.
What to do if you need help abroad
If you are abroad and you need emergency help from the UK government, you should contact the nearest British embassy, consulate or high commission.
If you need urgent help because something has happened to a friend or relative abroad, you should contact the Foreign and Commonwealth Office in London on 020 7008 1500 (24 hours).
For more information or travel advice, visit: gov.uk/foreign-travel-advice