"The proposed measures have been considered to be insufficient…[the strike will take place] from this moment until June 1," a union representative told the German RTL television broadcaster.
Police officers are demanding for airport security to be better equipped, the broadcaster added.
Earlier on Thursday, the Brussels Airport announced in a press release that its reopening has been approved by Belgium's fire services and the Belgian Civil Aviation Authority (BCAA). The reopening date has so far not been announced.
Labor unions had announced their decision to walk out over airport safety conditions on March 18, days before the terrorist attack took place.
Unions demand mandatory passenger checks to be conducted before entry into the temporary constructions erected in the wake of the attack for directing departures, the Belgian RTBF public broadcaster reported.
On Saturday, the airport announced that work on implementing additional security measures ordered by the Belgian government for all of the country's airports was underway, adding that the new security system will need to be approved by the authorities.
Two suicide blasts ripped through the Brussels Airport departure hall in the northeastern municipality of Zaventem on March 22. A further explosion occurred at the Maelbeek station near EU institutions. A total of 31 people, including 3 suicide bombers, died in the attacks. More than 300 were injured.