Dutch police arrested a “confused” homeless man suspected of triggering a security alert at Rotterdam airport yesterday.

This followed an anonymous tip-off about a possible terror threat which prompted the Foreign and Commonwealth Office to warn of an on going security operation at the airport.

Armed military police raised security at the regional airport after they received the anonymous call about an unspecified terror threat, according to Dutch media.

Officers with machine guns and wearing bulletproof vests checked and searched some cars and buses arriving at the airport.

More armed military police officers were stationed outside the entrance to the airport, which caters mainly for flights to the UK, Spain, Germany and other European destinations.

Flights were not affected in and out of the airport, which is about three miles north of Rotterdam, the busiest port in Europe, the AFP news agency reported.

An investigation was “immediately launched” after “an anonymous message indicating a possible threat at Rotterdam The Hague Airport” was received, the police said.

Royal Dutch Military Police said: “Rotterdam police have detained an illegal immigrant with an outstanding sentence in connection with their investigation into a possible terror threat.

“The suspect is a 45-year-old man without a fixed address and in a confused state, who has previously made similar false statements to the police.

“The man is believed to be involved in the tip-off and is being questioned as police think he may have some valuable information.”

The military police added that they had reviewed security measures in and around the airport, but gave no further details.

“Certain extra security measures, both visible and invisible, are being put into place,” the statement said, adding that Rotterdam mayor Ahmed Aboutaleb was being kept informed about developments.

Holland has been on high alert since the Paris attacks a year ago.

The Dutch counter-terrorism agency warned on Monday that jihadist fighters returning from Iraq and Syria amid an offensive against the Islamic State group could increase the risk of a terror attack.

Earlier this year a drunk Polish man sparked a late-night scare at Amsterdam’s Schiphol airport by falsely claiming to have a bomb in his backpack.

Police partially evacuated the airport during the incident, which came just three weeks after the March 22 attacks on Brussels airport and metro left 32 people dead and hundreds wounded.