Belgians identify two suspected bombers in Brussels blasts

* Attackers believed linked to suspected Paris attacker

* Blasts occur four days after Paris suspect held in Brussels

Belgian police identified two suspected Islamic State suicide bombers captured on security cameras before they struck Brussels Airport on Tuesday in the first of two attacks that also hit the city's metro, public broadcaster RTBF said on Wednesday.

The death toll in the attacks on the Belgian capital, home to the European Union institutions and Nato, rose to at least 31 with more than 200 wounded, Health Minister Maggie De Block said on VRT television.

The Syrian-based Islamist militant group claimed responsibility four days after the arrest in Brussels of a prime suspect in November's Paris attacks. If confirmed, the identifications would link the Brussels blasts directly to the jailed Paris suspect, Salah Abdeslam.

The attacks sent shockwaves across Europe and around the world, with authorities racing to review security at airports and on public transport, and rekindled debate about European security cooperation and police methods.

RTBF, quoting a police source, named the suspected bombers as Khalid and Brahim El Bakraoui, two brothers resident in Brussels and known to the security services for crime.

The newspaper DH said a third suspect seen with them before running away from the airport after the blasts was identified as Najim Laachraoui, 25, a man sought by police and directly linked to Abdeslam.

Khalid had rented under a false name the apartment in the city's Forest borough, where police hunting Abdeslam killed a gunman in a raid last week, RTBF said.

Policemen stand guard at the entrance of a security perimeter set around the Maalbeek metro station, in Brussels on Wednesday.

The Brussels blasts fuelled political debate across the globe about how to combat militants.

"We can and we will defeat those who threaten the safety and security of people all around the world," said US President Barack Obama.

Donald Trump, the front-runner for the Republican nomination to succeed Obama in November's US election, suggested suspects could be tortured to avert such attacks.

Brussels police searched a house in the north of the city late into the night, turning up another bomb, an Islamic State flag and bomb-making chemicals in an apartment in the borough of Schaerbeek.

Local media said authorities had followed a tip from a taxi driver who may have driven the bombers to the airport.

Investigators said they were focusing on a man in a hat who was caught on CCTV pushing a laden baggage trolley at the airport with two others they believed were the bombers. An unused explosive device was later found at the airport and the man, believed to be Laachraoui, was seen running away from the terminal after the explosions.

Closing in

Security experts believed the blasts, which killed about 20 people on a metro train running through the area that houses EU institutions, were probably in preparation before Fridaytarget="_blank"'>