"The airport will also be closed for passenger flights into and out of Brussels Airport tomorrow on 30 March," the airport said on Twitter after the authorities tested temporary check-in facilities and new security measures today.
Airport spokeswoman Anke Fransen said the decision had not been determined by the results of of the tests completed late afternoon.
"It was not a consequence of the simulation," Fransen said. "The different parties are each examining all the tests and the results will only be known tomorrow morning," she added.
"We hope to reach a decision on a partial re-opening of the airport in the course of the morning." Brussels airport is a major European hub and has flights to destinations worldwide.
The departure hall was packed on March 22 with Easter holiday-makers when the bombers struck. Chief executive Arnaud Feist warned earlier today that even if all the tests went well, "at best" about 20 per cent of services might be restored tomorrow. For a full return to normal, "we will have to wait for months," Feist told L'Echo daily.