Amsterdam - Dutch police on Thursday detained a man suspected of threatening an attack on a rock concert in Rotterdam, following a tip-off from Spain. The 22-year-old Dutch national was being questioned after being arrested around 2 a.m. during a raid in the southern province of Brabant, police said. Spanish police had earlier tipped off Dutch authorities about the potential attack on the Maassilo concert venue in Rotterdam, where Californian band Allah-Las were due to play on Wednesday night. The authorities did not specify how the threat had been disseminated. But Rotterdam mayor Ahmed Aboutaleb told reporters that the information from Spain had led directly to the suspect's arrest. The Spanish tipoff was "so accurate, that we could apprehend him" within hours, Aboutaleb said.