Dutch military police were on Wednesday investigating a major security alert triggered overnight at Amsterdam's busy international airport, with one man still in custody.
Dozens of heavily-armed military police had swooped on Schiphol airport, evacuating hundreds of people late on Tuesday from public areas after receiving a tip-off about a "suspicious situation."
The scare at one of Europe's busiest travel hubs with flight links around the world came exactly three weeks after the March 22 attacks on the Brussels airport and metro which left 32 people dead.
But it remained unclear exactly what was behind the late-night security sweep, after the Dutch bomb squad found nothing suspicious in the luggage of the arrested man.
"The man arrested in the suspicious situation in #Schiphol still in custody," the military police, said on their Twitter account.
They added they were "investigating" and would provide an update later in the day.
The man's identity has not been revealed.
No flights were disrupted during the operation, and the airport authorities confirmed no disruptions were expected on Wednesday.
Tensions have been high since last month's attacks in neighbouring Belgium, which like the November attacks in Paris, were claimed by the so-called Islamic State (IS) jihadist group.
There have been concerns that the Netherlands could be targeted in a terror attack, due to its proximity to both Belgium and France.
Dutch F-16 fighter jets have also broadened the country's mission in the US-led air campaign against IS, bombing jihadist targets in Syria since February.
As a precaution, the government stepped up security at national airports and train stations and tightened controls on its southern border with Belgium.
More than 200 Dutch nationals, including about 50 women, are also believed to have joined the ranks of IS in Iraq and Syria, according to Dutch intelligence services.
Last month, at the request of French authorities, Dutch police carried out raids on an apartment in Rotterdam, uncovering about 45 kilos of ammunition.
French suspect Anis Bahri was arrested at the flat suspected of trying to take part in a foiled plot in France. He is now fighting his extradition to Paris.
