BRUSSELS: A series of explosions claimed by the militant Islamic State (IS) group ripped through Brussels airport and a metro train on Tuesday, killing around 35 people in the latest attacks to bring bloody carnage to the heart of Europe.

Two huge blasts, at least one of which prosecutors said was likely caused by a suicide bomber, rocked the check-in hall at Zaventem Airport, strewing the scene with blood and mangled bodies and sending hundreds of terrified travellers fleeing in terror.

The fact that extremists were able to hit high-profile targets in Brussels, Europe`s symbolic capital, just months after IS militants killed 130 people in Paris, will raise fresh questions about the continent`s ability to cope with the terrorist threat.

More than 200 people were wounded in the bloodshed, which came just four days after the dramatic arrest inBrussels of Salah Abdeslam the prime suspect in the Paris attacks after four months on the run.

Belgian authorities had been on alert after Abdeslam, Europe`s most wanted man, told investigators he had been planning an attack on Brussels.

An online news agency affiliated with IS said the group was behind the attacks.

`Islamic State fighters carried out a series of bombings with explosive belts and devices on Tuesday, targeting an airport and a central metro station in the centre of the Belgian capital Brussels, a country participating in the international coalition against the Islamic State,` the Aamag news agency said.

Hundreds of flights and trains were cancelled as security across Europe was tightened after the bombings, which Belgian Prime Minister Charles Michel termed `blind, violent and cowardly`.

`This is a day of tragedy, a black day,Michel said. His spokesman announced three days of national mourning.

Shortly after the airport blasts at about 8am, a third explosion rocked Maalbeek metro station, in the heart of the city`s EU quarter, as rush-hour commuters were making their way to work.

The blast hit a train as it left the station, heading to the city centre. A news organisation carried a photograph of a metro carriage at a platform with doors and windows completely blown out, its structure deformed and interior mangled and charred. A local journalist tweeted a photograph of a person lying covered in blood among smoke outside the station. Ambulances were ferrying the wounded away and sirens rang out across the area.

Three suspects More suspects could still be at large in Brussels, home to the headquarters of both Nato and the European Union, Belgian Foreign Minister Didier Reynders warned.

Belgian authorities published surveillance camera images showing three male suspects going past the check-in area. Two had dark hair and one was wearing a hat.

Pierre Meys, spokesman for the Brussels fire brigade, said at least 14 people had been killed at the airport, while Brussels mayor Yvan Mayeur said `around 20` died in the underground blast.

Witnesses described horrific scenes at the airport, with victims lying in pools of blood, their limbs blown off.

Authorities later said a third bomb had failed to explode at the airport.

At Maalbeek station, paramedics tended to commuters with bloodied faces as the city`s normally peaceful streets filled with the wailing of sirens.

Leaders across Europe reacted with outrage to the attack on the EU`s institutional capital, urging closer counterterrorism cooperation on a continent that has been on high alert for months.-Agencies