Brussels airport cancelled around 50 flights on Wednesday due to a second day of industrial action by air traffic controllers, the Belga news agency reported.
The strike comes as the airport has sought to recover from suicide bombings last month in which two attackers blew themselves up in the departure hall. Together with a third blast at a Brussels underground station, 32 people were killed.
Belgium's main international aviation hub was closed for several days, and services have yet to return to normal. The airport should have been handling around 400 flights Wednesday, according to Belga.
"Much effort has been invested to resume activities and win back the confidence of foreign aviation companies," Belgian Employment Minister Kris Peeters said Wednesday, Belga reported. "The current actions are seriously complicating this new beginning."
The airport's website carried an advisory Wednesday telling passengers to check the status of their flight before setting off.
Roughly 100 flights were cancelled Tuesday due to the strike, and seven were diverted abroad, Belga reported.
The industrial action began hours after the airport settled a dispute with air traffic control representatives, reaching a compromise deal under which employees will gradually see their working age extended.
The agreement "does not satisfy the guild of air controllers," aviation operator Belgocontrol said in a statement Tuesday, adding that staff members were claiming to be ill and unable to work.
The decision to go on strike so soon after the terrorist attacks drew criticism at home and abroad.
On Tuesday, the International Air Transport Association (IATA) had condemned the action as a "kick in the teeth" for all those who had worked to get the airport up and running again.
"It is the height of irresponsibility to cut a vital service, and doing so without warning can only be seen as malicious," IATA chief executive Tony Tyler said in a statement.