Amsterdam: Dozens of heavily-armed military police swooped on Amsterdam`s Schiphol airport late Tuesday, evacuating part of the busy travel hub and arresting one man, triggering a four-hour security alert.
The incident came as the Netherlands has been on high guard following the March 22 attack on the Brussels airport and metro in which 32 people were killed.
"Police have evacuated part of the airport plaza and the adjacent Sheraton Hotel and arrested one person amid a suspicious situation," airport spokeswoman Danielle Timmer told AFP.
AFP reporters saw heavily armed Dutch special military police, wearing balaclavas, patrolling the airport while passengers anxiously watched from behind security tape.
Part of the airport was cordoned off for about four hours while a helicopter hovered overhead, until the alert was lifted at around 1:30 am (2330 GMT).
It remained unclear exactly what had triggered concerns, or who had been arrested, but the Dutch news agency said nothing dangerous had been found in a search of the arrested man`s luggage.
Military police spokesman Alfred Ellwanger told AFP that "around 9:45 pm a man was arrested on the square in front of the main entrance to the airport`s plaza".
No flights were disrupted and trains continuing arriving as normal at the underground station, which links the huge travel hub to the rest of the Netherlands.
"Nobody is telling us anything about what`s going on. My car is in the parking garage and I can`t get it out. I`m a diabetic and I need my insulin," said a 72-year-old Dutchman.
Schiphol, which lies about 16 kilometres (10 miles) southwest of central Amsterdam, is one of Europe`s busiest travel hubs with about 50 million visitors passing through each year.
"Part of Schiphol is not accessible due to an incident. Police is investigating the matter. For now, air traffic has not been affected," the airport said on its official Twitter account.
A spokesperson for the 407-room Sheraton hotel, which is linked to the airport via a covered walkway, reached by AFP declined to comment.Schiphol`s busy modern plaza and entrance is usually crowded with passengers and visitors, many of them enjoying a meal at one of the eateries or perusing the shops.
Tensions have been high since last month`s attacks in neighbouring Belgium, which like the November attacks in Paris, were claimed by the Islamic State (IS) jihadist group.
One person was also arrested at the nearby Leiden railway station for raising a "false alarm", a spokeswoman for The Hague police told AFP.
Another person was arrested at Schiphol, but unrelated to the incident, police said.
There has been concern in the Netherlands about whether it could potentially be targeted in a terror attack, due to its proximity to both Belgium and France.
As a precaution, the government stepped up security at national airports and train stations and tightened controls on its southern border with Belgium.
Dutch police carried out raids in Rotterdam last month, uncovering about 45 kilos (99 pounds) of ammunition in one apartment linked to a foiled attack on France.
French suspect Anis Bahri was arrested at the flat in the southern port on March 27 at Paris` request, amid suspicions he was planning an attack in France for the Islamic State group.
He is fighting his extradition to Paris, where he is wanted on suspicion of plotting the foiled attack with another man, Reda Kriket.
Two Algerians arrested with Bahri have been remanded in custody in the Netherlands.