Police working at Brussels Airport have claimed that at least 50 Islamic State supporter are working at the airport as baggage handlers, cleaners and catering staff – and that some of them still have access to the cockpits of the planes despite concerns being raised. The police are now threatening strike action unless security is taken seriously.

Fearing workers may be briefing terrorists on the best locations to launch an attack, the Belgian police union, NSVP warned the interior ministry on the 18th March that they would strike unless more was done to make the airport secure. Just four days later, on the 22nd, three terrorists walked into Brussels airport and detonated two bombs.

A third failed to detonate, sending the unidentified terrorist fleeing.

Two of the bombers involved in the attack, brothers Ibrahim and Khalid el-Bakraoui, have since turned out to have worked at the airport. A man who identified himself as their uncle but asked not to be named has told the Daily Mail: “They worked cleaning at the airport and in a restaurant. They didn’t finish high school in the end. They cleaned the airport in the summer months.”

That work would have given them intimate knowledge of the layout of the airport and its security practices. Ibrahim went on to detonate his bomb at the airport alongside bomb-maker Najim Laachraoui, while Khalid targeted the metro transport system.

Alain Peeters, the general secretary of NSVP, said: “The sad events of 22 March demonstrate that our concerns are justified. We demand more security and more staff.”

Officers are refusing to return to work when the airport reopens unless their demands for more staff are met. They are also insisting that vehicles must not be allowed within 100m of the new temporary check-in hall currently under construction.

Such is their level of frustration they have penned an open letter detailing the security failures at the airport which helped the terrorists strike.

“Some people suspected of having fought in Syria came to the airport as “false tourists”. We reported their presence but we do not know if anything was done with that information,” they wrote.

And they said they had raised suspicions about a number of their fellow airport workers, some of whom had apparently celebrated after the Paris attacks last November.

“When we checked these people, we were surprised more than once. It was men with a radical ideology and a long police history.

“Even today, there are at least 50 supporters of the Islamic State who work at the airport. They have a security badge and have access to the cockpit of a plane.

“In the past, a number of people had their badges revoked because they had IS sympathies. But clearly not everyone, especially in store personnel, cleaning services and baggage where we find the most suspicious people.”

The Belgian authorities have repeatedly been accused of ignoring warnings which could have prevented last week’s attack and saved 35 lives.

The Turkish President Recep Tayyip Erdoğan has lambasted Belgium for ignoring information naming Ibrahim El Bakraoui as a terrorist fighter when he was deported from Turkey to the Netherlands last summer.

Erdoğan said “despite our warnings that this person was a foreign terrorist fighter, Belgium could not establish any links with terrorism.”

According to ZeroHedge, he later told Romanian media: “One of the attackers from yesterday from Brussels is someone that we expelled. We notified the Belgian authorities about this, but they let him go free. The Netherlands is also involved in this. We expelled him upon request from the Dutch authorities and we sent them a note.”