Brussels airport authorities have said they are ready to resume flights from the bomb-damaged facility soon, but not before the weekend.

Belgium's civil aviation authority and the fire department have given their approvals to a reopening following testing on Tuesday, one week after the suicide bombings.

Operating company Brussels Airport said in a statement that the airport is "technically ready for a restart of passenger flights in the temporary infrastructure foreseen for check-in".

Flights will resume once political approval to reopen is granted, but not before Friday evening. Due to the damage, the airport will be able to run only at 20% of normal capacity.

The area where arriving passengers transit was only slightly damaged and is ready for use.

The move comes after police at the airport said they had criticised the lack of security at Belgium's main transport hub well ahead of the attacks on March 22.

In an open letter to their superiors and the airport authorities, police said they had sent "strong daily signals regarding the overall security at the airport".

They complained that "there had not been any security control of passengers or luggage from the airport complex right up to the centralised body searches" area.

The letter said the lack of security was such that police fear "scouts were sent out to assess the security lapses and plan terror".

The airport police also complained that too many airport employees have criminal backgrounds.