A van with Spanish licence plates and containing gas bottles has been found near a Rotterdam concert hall where earlier on Wednesday a rock concert was cancelled due to a threat.
However it was not connected to the attacks in Catalonia, Spain, last week, a judicial source told Reuters.
The source said the tip given by Spanish authorities to their Dutch counterparts was the result of an investigation by the Spanish Civil Guard which had been under way for some time, and had no direct relation to the two vehicle attacks in Barcelona and Cambrils that killed 15 people and injured dozens.
Another police source said the man arrested in Rotterdam was Spanish and was being questioned. A bomb squad was examining the van.
Police said the concert, which was to feature Californian band Allah-Las, was cancelled about 7pm (local time), shortly before doors were to be opened for guests, after a tip from Spanish police.
As concert-goers were sent away from the Maassilo, a former grain silo complex on the Maas river that has been converted into an event hall, the venue was cordoned off.
No arrests or detentions were reported until the bus driver was detained about 9pm.
The National Coordinator for Security and Counterterrorism's office said the threat level in the Netherlands was unchanged at "substantial", where it has been since 2013.
Spanish police declined to comment.
