The second suicide bomber who blew himself up at Brussels airport has been identified as Najim Laachraoui, police sources told AFP on Wednesday.

Belgian prosecutors earlier identified Ibrahim El Bakraoui as the other bomber and said a third suspect whose bomb failed to go off was still being hunted.

Ibrahim's brother Khalid carried out a suicide attack at Maalbeek metro station in Tuesday's coordinated attacks in the Belgian capital.

Moroccan-born Laachraoui's DNA was found on explosives used in the November 13 Paris attacks as well as at an apartment in Brussels where bomb-making equipment and a fingerprint from Salah Abdeslam -- prime suspect in the Paris attacks -- had been found in December.

The blasts in Brussels occurred four days after Abdeslam's arrest.

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 Franco-Moroccan Abdeslam and Algerian Mohamed Belkaid, who was killed in a March 15 Brussels raid, three days before Abdeslam was captured.

Belkaid is believed to have provided logistical support to the Paris attackers.