The attacks on Tuesday put the Belgian capital in a state of virtual lockdown, with the threat level raised to its highest possible level. (AFP File Photo)
More than 30 people have been identified as being involved in a network behind the Paris attacks on November 13, with links now established to this week's bombings in Brussels where at least 30 people were killed in triple blasts.
This is what we know so far about the attackers and their support network.
Brussels airport, metro attacksFour people carried out coordinated attacks at Brussels airport and a metro station on March 22 that left 31 dead and wounded 300.
Two brothers, Khalid and Ibrahim El Bakraoui were identified as suicide bombers -- one at Zaventem airport and one at Maalbeek metro station.
Najim Laachraoui, 24, was identified as the second airport bomber and is believed to have made bombs for the November rampage in the French capital.
A third person seen on airport surveillance footage wearing a white jacket is the subject of a police manhunt after he fled the scene when his explosive-packed suitcases did not detonate.
Salah AbdeslamBrussels had already been on alert as the home and hideaway of several of the Paris attack suspects.
The last surviving member of the cell directly involved in the Paris assaults, Salah Abdeslam, was arrested in Brussels four days before the twin airport and metro assault.
Abdeslam, 26, said he was planning further attacks in Brussels, and links have emerged between him and the suspected Brussels assailants.
He is believed to have played a key logistical role in the Paris attack, renting cars and an apartment-hotel used by the jihadists.
Abdeslam has told investigators he had planned to blow himself up outside the Stade de France on the evening of the Paris attacks but changed his mind.
Brussels-Paris linksThe Bakraoui brothers had been sought by police for links to Abdeslam prior to the Brussels attacks.
Belgian television said Khalid had rented an apartment in Brussels last week under a false name where Abdeslam's fingerprints were found after a bloody police raid.
He is also linked to another apartment in southern Belgium that Abdeslam and other jihadists used before the Paris attacks.
DNA from the second airport suicide bomber Laachraoui, 24, was found at an apartment in Brussels where bomb-making equipment and one of Abdeslam's fingerprints had been found in December. His DNA was also found on explosives used in the Paris attacks.
Prosecutors have said Laachraoui "travelled to Syria in February 2013," and was registered under a false name at the border between Austria and Hungary last September.
He was travelling with Abdeslam and Mohamed Belkaid, who was killed in a Brussels raid three days before Abdeslam was captured.
Belkaid is believed to have provided logistical support to the Paris attackers.
Paris attacksA 10-man team of suicide bombers and gunmen launched attacks on the Bataclan concert hall, the Stade de France national stadium and a string of bars and restaurants around eastern Paris on the night of November 13, 2015.
Seven of the attackers died on the night, and two more were killed the following week. The last member of the team, Salah Abdeslam, was arrested in Brussels on Friday after four months on the run.
The coordinated assaults claimed by the Islamic State group killed 130 people and wounded another 350.