Police in the port city of Rotterdam have detained the driver of a van with Spanish registration plates and gas tanks inside after a concert by an American rock band was cancelled following a threat.

A Spanish counter-terrorism official said the van was not connected to the attacks that killed 15 people last week.

The official said investigators discarded a possible link between the van's driver and the extremist cell that carried out the attacks in and near Barcelona after questioning the driver and examining the van.

Police detained the driver for questioning about two hours after a concert by Los Angeles band Allah-Las was called off after Dutch police received a terror warning.

Rotterdam mayor Ahmed Aboutaleb said the warning came from Spanish police, but said it was too soon to link the van to the unspecified threat directed at the concert.

"It is not yet good to say that the things are linked," he said.

"It still has to be established that there was a link between the van and the threat. We can't say that yet."

Military explosives experts checked the van and a police officer later drove the vehicle away, Dutch broadcaster NOS said.

Police said the van contained "a couple of gas bottles".

The Dutch terror threat, which is at level four of a five-step scale, remained unchanged, Lodewijk Hekking, a spokesman for the country's anti-terror chief, said.

The Spanish anti-terrorism 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.

Police in Spain have been investigating the deadly vehicle attacks last week in and near Barcelona.

They later found bomb-making equipment that included more than 100 tanks of butane gas, nails and 500 litres of acetone.

Rotterdam police said they took the information about a threat "seriously enough that after discussion with organisers it was decided to cancel the event".

Concert organiser Rotown said earlier on Twitter that the venue, a former grain silo called Maassilo, was being evacuated because of the unspecified threat.

The show had not yet started when the decision to cancel it was made.

Dutch television showed officers in body armour outside Maassilo and what appeared to be members of the band leaving the venue in a white van with a police escort.

By around midnight the area was calm and police had lifted the cordon they earlier put up around the venue.

Allah-Las is a four-piece band from Los Angeles.

The band's label, Mexican Summer, said: "Due to a potential terror threat at The Maassilo in Rotterdam, the Allah-Las show was cancelled tonight.

"Details are not available at this time as the incident is still under investigation.

"The band is unharmed and are very grateful to the Rotterdam police and other responsible agencies for detecting the potential threat before anyone was hurt."

In an interview with The Guardian last year, band members said they chose the word Allah, Arabic for God, because they were seeking a "holy sounding" name and did not realise it might cause offence.

"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 told the newspaper.

"We email back and explain why we chose the name, and mainly they understand."

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.