Air traffic controllers at Brussels' international airport suspended their strike Wednesday after hampering operations for 24 hours, but Belgium's main aviation hub warned that the situation for the following day was unclear.
The strike came 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.
The airport was closed for several days, and operations have yet to return to the full capacity prior to the attack. The airport should have been handling around 400 flights Wednesday, but around 50 of them were being cancelled, Belga reported earlier in the day.
At 5 pm (1500 GMT), the airport announced that "all flights will leave or land as planned" until 10 pm. "The situation as of 22:00 and tomorrow is still unclear," it wrote on its website. "We expect new problems," a spokesman told Belga.
Wednesday's resumption of services came after an appeal by Belgian Prime Minister Charles Michel for the air traffic controllers to end their strike.
"It's a wildcat strike, it is totally unacceptable. This is an irresponsible strike," Michel said, according to Belga. "I do not accept that a handful [of people] decides to take the country hostage, to put our image and our economic situation in danger."
The industrial action began hours after the airport settled a dispute with air traffic control representatives on Tuesday, 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 later said in a statement, adding that staff members were claiming to be ill and unable to work.
The International Air Transport Association (IATA) had also condemned the decision to strike so soon after the terrorist attacks 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 issued Tuesday.