Islamic State has claimed it carried out the deadly attacks on Brussels.
The militant group claimed responsibility for the two attacks in a statement released on its official account with the social media site Telegram.
It 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.”
Belgium is one of dozens of countries which have met to discuss tackling the group, which has taken large swathes of territory in Syria and Iraq.
Earlier, the AMAQ news agency, which is affiliated to the jihadist organisation, said: “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.”
At least 34 people have been killed in two attacks on the Belgian capital’s Zaventem Airport and metro system.
The blasts came four days after the arrest of Salah Abdeslam, who authorities believe took part in November’s attacks on Paris, which were also claimed by IS.
Shots were fired as the attackers at the airport reportedly shouted in Arabic before two explosions.
About 70 minutes later, Maalbeek metro station near the EU offices was targeted in a separate attack during the morning rush hour.
Police released a photo showing three men who could be involved in the bombings, pushing trolleys, and said that one of them is on the run.
Belgian police say they believe that the men were part of a larger cell and US officials said they believe the bombers were most likely carried out by militants linked to Abdeslam.
Some commentators said that the successful attacks showed that Belgium’s security arrangements were lacking.
Pini Schiff, CEO of the Israel Security Association, said: “Two terrorists who enter the terminal area with explosive devices, this is undoubtedly a colossal failure.”