Dutch police conducting a major terror investigation after a tip-off from Spain arrested a second suspect on Thursday near the port city of Rotterdam.
A 22-year-old man was held in a raid on a private home just hours after a concert by a US rock band was cancelled on police orders. Officials would not say if the Spanish warning was related to the Barcelona attack that killed 15 last week.
The Barcelona terror cell with links to ISIL is known to have had contacts with extremists in France and possibly Belgium..
Frank Paauw, a police chief in Rotterdam, said the arrest of a man suspected of being "involved in the preparation of a terrorist attack” meant the specific alert that forced the shutdown of the concert was over.
"There is no threat because we have arrested a suspect and the information about the threat was so specific on the location of the event that with that arrest we can conclude that the threat is gone,” he said.
Police squads discovered a hand grenade near the venue. More than 900 ticket holders were sent home after the performance was cancelled.
The discovery of a van packed with household gas canisters appears to have triggered concerns about a plot similar to the one under investigation in Spain, as the van had Spanish plates and was driven by a Spanish national and there were a couple of gas bottles.
The Dutch police later said that while the van had aroused suspicion, the driver was inebriated and presented no assessed threat when questioned.
Meanwhile the government of Catalonia admitted it had received a warning about one of the Barcelona plotters, Abdelbaki Es Satty, who died in an explosion in a house the day before the attack in the city. The warning came from a Dutch speaking town in Belgium.
"The imam of Diegem asked about the man who had moved to Vilvoorde," Hans Bonte, the mayor of Vilvoorde in Belgium, told the Spanish newspaper, El País. "He said he acted strangely and told him he'd left Spain because he had no future there and had proclaimed himself imam, though he had no accreditation."
No action was taken by the Catalonia authorities to follow up on the information.
In Rotterdam the Californian band which was due to play the concert thanked the police for a smooth evacuation of the venue. Its members have spoken in the past of receiving threats related to the band's name, Allah-Los. "We get emails from Muslims, here in the US and around the world, saying they're offended, but that absolutely wasn't our intention," lead singer Miles Michaud said last year. "We email back and explain why we chose the name, and mainly they understand.”
The incident comes months after a Dutch man — who was known to authorities as being possibly radicalised — was arrested filming outside one of the country's largest stadiums during a concert.
The 29-year-old from Amsterdam was detained in June outside the Philips Stadium in southern Eindhoven where popular Dutch pop singer Guus Meeuwis was performing. Police said at the time, "He had no reasonable explanation for what he was doing, and also had no ticket to the concert." The performance ended without incident.
It followed an attack in May at the end of a concert in Manchester by US singer Ariana Grande in which a suicide bomber killed 22 people including seven children.
