An investigation into the Brussels suicide bombings last year highlighted failures in intelligence sharing among the security services as well as their "limited" information about radical networks.
The parliamentary committee probe also found that the security services failed to thoroughly follow up information about the men would carry out the attacks on the metro and airport in March 2016 that killed 32 people.
"The absence of an information-sharing culture constitutes the main gap within and among the security services," the report said.
Fifteen years after major reforms, the committee complained of "compartmentalisation which blocks comprehensive information management".
Belgian security experts said just after the attacks there was little sharing of information among the six police zones in Brussels or between the federal police and local police or between the state security services and local forces.
The report said there was a failure to follow up in the cases of Khaled and Ibrahim El Bakraoui before the former blew himself up at Maalbeck metro station and the latter set off his suicide bomb at Zaventem airport.
Turkish President Recep Tayyip Erdogan claimed that Belgium ignored intelligence about Ibrahim El Bakraoui after Turkey arrested him near the Syrian border as a "foreign terrorist fighter" and deported him in June 2015.
It recommended that the security services deploy liaison officers at Belgian embassies in countries that play an important security role, such as in Turkey.
"The information position of our security services is too limited in radical circles and on social networks, for example," the report said.
The Islamic State, which claimed the Brussels attacks, communicate using social networks.
The report also recommended better coordination among the different police, intelligence and security services as well as reinforcing and streamlining their resources.
It called for better handling of evidence or potential evidence, referring to the February 2015 seizure of the cell phone of Brahim Abdeslam, who took part in the November 2015 Paris attacks, in a drugs case.
An analysis of the phone's contents revealed nothing and officers did not follow up until after French police found that Brahim Abdeslam had blown himself up in Paris and that his brother Salah Abdeslam was a fugitive in the case.
But it said the phone had disappeared and was only found a year later under a pile of papers in the Brussels police station where Brahim Abdeslam had been questioned in the drugs case.