A van with Spanish registration plates and containing gas bottles found near a concert hall in Rotterdam is not connected to the attacks in Catalonia last week, a Spanish judicial source says.

Dutch authorities closed down a music venue in Rotterdam and sent away concert-goers before a show by Californian band Allah-Las was due to get underway at 7pm (local time) Wednesday night after receiving advice of a terror threat from Spanish authorities.

The Spanish source told Reuters that the tip-off 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 in Catalonia that killed 15 people.

Police arrested a Spanish bus driver two hours after the tip-off and the bomb squad is investigating the bus and gas cylinders found inside it.

Rotterdam Mayor Ahmed Aboutaleb said it was too early to draw a link between this latest incident and the deadly attacks in Catalonia in Spain last week.

“It would be wrong at this moment to pile up these facts and conclude: thus there was a plan to attack with gas bottles, et cetera, because that was the picture last week in Barcelona. I would be careful with that,” Aboutaleb said.

Police said the concert was cancelled shortly before doors were to be opened for guests.

As concert-goers were sent away from the the Maassilo, a former grain silo converted into a band venue on the Maas river, the area was cordoned off.

A Spanish counter-terrorism investigation official said Spain’s Civil Guard received “an alert indicating the possibility of an attack today in a concert that was going to take place in Rotterdam”.

The Civil Guard shared the information with Dutch authorities and is investigating the threat, the source said, speaking anonymously because the Civil Guard is still probing the threat.

The Netherlands National Coordinator for Security and Counterterrorism’s office said the threat level in the country was unchanged at “substantial”, where it has been since 2013.

In an interview last year, the Allah-lahs told The Guardian newspaper they regularly received messages from Muslims offended by the use of the word Allah in its name.

The group said it had wanted a religious-sounding name after being inspired by the group Jesus and Mary Chain.