In a statement released through one of its propaganda outlets, the so-called Islamic State said: "Explosive belts and devices" were used to massacre passengers checking in at Brussels Airport and on a Metro train, The Daily Star wrote.
"Islamic State fighters opened fire inside Zaventem Airport, before several of them detonated their explosive belts, as a martyrdom bomber detonated his explosive belt in the Maalbeek Metro station," a spokesperson said.
"We promise the crusader alliance against the Islamic State that they will have black days in return for their aggression against the Islamic State.
"And what will await you will become harder and more bitter through the grace of Allah.
"In praise of Allah who has made our blows precise and helped us succeed. We demand for him to accept our brothers among the martyrs."
As UNIAN reported earlier, two explosions hit the Brussels airport early on Tuesday morning.
Following the attack on the airport, the explosions hit metro stations, close to the European Union's administrative buildings.