Staff from Belgium's air traffic control firm Belgocontrol were protesting on Tuesday against attempts to raise their retirement age as well as other terms of their labor contract. A statement from Belgocontrol merely said that the controllers were "sick" and that it "was looking for operational solutions."

The Geneva-based trade group International Air Transport Association condemned the action in no uncertain terms, saying it was "kick in the teeth for all the airline and airport staff who have worked so hard to reconnect Brussels to the world" after the jihadist bombings in the check-in area.

No flights landed or took off from Brussels for several hours on Tuesday as a result of the strike. The facility only reopened on Sunday after coordinated blasts on March 22 at the airport and a metro station killed a total of 32 people.

Earlier on Tuesday, police had blocked off access to the airport for three hours after a "suspicious vehicle" was found parked outside, but authorities later said it was not a threat.

es/rc (AFP,dpa)