The head of Schiphol airport in Amsterdam, one of Europe’s busiest aviation hubs, has warned that the number of armed military police it has on duty is inadequate to deal with increasing terrorist threat levels.

In unusually forthright comments aimed at securing extra funding from the incoming government after the March election, the airport’s director, Jos Nijhuis, said that while there were already 1,800 military police stationed there, the current plan to add another 135 was still “inadequate”.

“Another 135 would simply put us at about the same level as in 2008 and 2009, but the reality is that both the number of passengers and the terrorism threat have increased sharply on what they were eight years ago – so action must be taken now,” he urged.

Mr Nijhuis calculated that the airport needed between 400 and 500 more officers to provide adequate security “in the light of increasing terrorism threats”.

The strategic importance of Schiphol was underlined when the deputy national counter-terrorism co-ordinator for the Netherlands, Wilma van Dijk, was named director of security at the airport towards the end of last year.

Following attacks by Islamic State in Paris, Brussels, Nice, Istanbul and Berlin, the terror threat level in the Netherlands stands at “substantial”, its second-highest – which means that the chance of an attack is “real” but there is no specific intelligence indicating when.

Credible ‘signal’

After the Brussels airport bombings, the threat to hubs such as Schiphol moved a step closer to reality when the Dutch authorities were forced to supplement the military police with elite troops from the 11th Air Assault Brigade in response to a credible “signal” that an attack was likely.

The troops carried out stop-and-search patrols in and around the airport for a fortnight at the height of the holiday season, when about 200,000 passengers pass through every day – causing traffic chaos and delays to flights. They left the airport towards the end of August.

The problem for the military police service, said Mr Nijhuisen, was that as well as being understaffed, it was under pressure to deal with illegal migrants elsewhere, as well as providing security for Jewish synagogues, schools and other potentially vulnerable locations.

“On top of that, Schiphol airport has just had the busiest year in its history. In 2015, there were just a few days when we handled more than 200,000 passengers. But last year there were 40 days when we broke that barrier, and 2017 will be even busier.

“That raises questions. For instance: what happens at Schiphol airport when an incident occurs elsewhere in the Netherlands and the military police are pulled away? Just because we got through a record 2016 does not mean we can relax for one moment.”