By Agence France-Presse
"There was concrete information from the Spanish police that an attack would be committed on that date, at this place and against this rock band," the port city's police chief Frank Paauw told reporters.
Spain was rocked last week by twin vehicle attacks which killed 15 people and wounded 120, but it remained unclear whether the tip-off to the Dutch came before or after Spanish police began investigating the incidents.
After cancelling a planned concert by the Californian band Allah-Las in Rotterdam, Dutch police swooped on a house in the southern Brabant region before dawn Thursday "and arrested a 22-year-old man regarding the terror threat Wednesday evening in Rotterdam".
They also carried out "an extensive search" of the premises, police said in a statement.
But there were growing doubts that another man, arrested late Wednesday in the port driving a van with Spanish licence plates and carrying gas canisters close to the Maassilo concert hall, was linked to the terror threat.
The van driver, a mechanic who "appeared to be under the influence of an alcoholic substance, was detained and transferred to a police facility" on Wednesday, police said, adding officers had found a "couple of gas canisters" in his van.
"His house was searched last night and no link with the terror threat was found. The man is still detained and will be questioned when sober," police said in an English statement.
While Spanish police appeared to rule the man out of the inquiry, Paauw said his team were still investigating but it seemed likely "the man had had the bad luck to be in the wrong place at the wrong time."
- Concert attacks -
The news follows a suicide bombing of a concert by US singer Ariana Grande in the English city of Manchester in May which killed 22 people.
And in November 2015, 130 people were killed in Paris when as part of a series of attacks jihadists hit the Bataclan concert hall where US rock band Eagles of Death Metal were playing.
"After what happened in Barcelona, I think the police really took the situation seriously and didn't want to take any risks in Rotterdam," witness Usama Mohamed told AFP.
Spanish police said Thursday they had identified the remains of the last suspected member of the cell believed to have carried out the August 17 attacks in northeastern Spain.
Youssef Aalla died in an accidental blast at the jihadists' bomb factory on the eve of the assault.
The blast forced the group to use vehicles instead as weapons, ploughing into pedestrians on Barcelona's busy Las Ramblas boulevard and a promenade in the resort of Cambrils.
- 'Holy' name -
On Wednesday Dutch authorities decided to cancel the Allah-Las concert after the tip-off from Spanish police around 5:30 pm (1530 GMT).
The four-piece band, from Los Angeles, was escorted from the concert hall by police wearing bullet-proof vests.
In a statement sent to AFP, they said they were "unharmed and are very grateful to the Rotterdam police and other responsible agencies for detecting the potential threat before anyone was hurt".
The eclectic band refused to comment further. In an interview with the British daily The Guardian last year, they said they receive emails from Muslims offended by their name, but "that absolutely wasn't our intention".
They said they chose to use Allah -- Arabic for god -- because they wanted something "holy sounding".
The Netherlands has so far been spared from the slew of terror strikes which have rocked its European neighbours recently.
But concerned top Dutch security and intelligence officials have been keeping a wary eye on events.
In June, a Dutch man -- known to authorities as being possibly radicalised -- was arrested filming outside one of the country's largest stadiums during a concert. He was later freed, but the incident is still under investigation.