Spain's royals condemned the attack in Barcelona on Thursday in which a van ploughed through crowds of pedestrians, killing at least 13 people, saying the country would not be "terrorised."

"They are assassins, criminals who won't terrorise us. All of Spain is Barcelona," the royals tweeted in an unusually strongly-worded statement, joining Spanish Prime Minister Mariano Rajoy who said "terrorists will never defeat a united people."