Islamic state threaten more countries after Brussels attack
Extremists behind the Brussels attacks have warned of more strikes against anti-Islamic State allies after bombers killed at least 34 people and wounded scores of others.
The back-to-back bombings of Zaventem Airport and Maelbeek underground station again laid bare Europe's vulnerability to suicide squads.
IS later warned of further attacks, issuing a communique promising "dark days" for countries taking part in the coalition against the terror group.
Bloodied and dazed travellers staggered from the airport after two explosions - at least one blamed on a suicide attacker and another apparently on a suitcase bomb - tore through crowds checking in for morning flights.
About 40 minutes later, another rush-hour blast ripped through a train carriage in central Brussels as it left Maelbeek, in the heart of Belgium's capital.
Authorities released a CCTV photo of three men pushing luggage trollies in the airport, saying two of them apparently were suicide bombers and that the third, dressed in a light-coloured coat, black hat and glasses, was at large. They urged the public to contact police if they recognised him.
The two men believed to be the suicide attackers were wearing dark gloves on their left hands, possibly to hide detonators.
In police raids across Belgium, authorities later found a nail-filled bomb, chemical products and an IS flag in a house in the Schaerbeek neighbourhood.
In its claim of responsibility, IS said its members detonated suicide vests both at the airport and in the station, where many passengers fled to safety down dark tunnels filled with hazy smoke from the explosion. A small child wailed and commuters used mobile phones to light their way out.
The government said at least 11 people were killed at the airport and 20 on the tube. Later, a security official said the overall death toll had risen to 34.
European security chiefs have been bracing for a major attack for weeks and warned that IS was actively preparing to strike. The arrest on Friday of Salah Abdeslam, a key suspect in the November 13 attacks in Paris, heightened those fears, as investigators said many more people were involved than originally thought and that some were still on the loose.
"In this time of tragedy, this black moment for our country, I appeal to everyone to remain calm but also to show solidarity," said Belgian prime minister Charles Michel, who announced three days of mourning in his country's deadliest terror strike.
"Last year it was Paris. Today it is Brussels. It's the same attacks," said French president Francois Hollande.
Shockwaves from the attacks crossed Europe and the Atlantic, prompting heightened security at airports and other sites.
Belgium raised its terror alert to the highest level, shut the airport throughout Wednesday and ordered a city-wide lockdown, deploying about 500 soldiers onto Brussels' largely empty streets to bolster police checkpoints. France and Belgium both reinforced border security.
Justice and interior ministers from across the 28-nation European Union planned an emergency meeting, possibly for Thursday morning, to assess the fallout. The station blast was beneath buildings that normally host EU meetings and house the bloc's leadership.
Medics said some victims lost limbs, while others suffered burns or deep gashes from shattered glass or suspected nails packed in with the explosives. Among the most seriously wounded were several children.
The bombings came barely four months after suicide attackers based in Brussels' heavily Muslim Molenbeek district slaughtered 130 people at a Paris nightspots, and intelligence agencies had warned for months a follow-up strike was inevitable. Paris fugitive Abdeslam was arrested in Molenbeek.
A top Belgian judicial official said a connection by Abdeslam to Tuesday's attacks was "a lead to pursue".
Abdeslam has told investigators he was planning to "restart something" from Brussels, said Belgian foreign minister Didier Reynders. He said authorities took the claim seriously because "we found a lot of weapons, heavy weapons in the first investigations and we have seen a new network of people around him in Brussels".
While Belgian authorities knew that some kind of extremist act was being prepared in Europe, "we never could have imagined something of this scale," Belgian interior minister Jan Jambon said.
Zaventem airport officials said police had discovered a Kalashnikov assault rifle and an explosives-packed vest abandoned there, offering one potential lead for forensic evidence. Bomb disposal experts safely dismantled the explosive device.
American intelligence officers are working with their European counterparts to try to identify the apparently skilled bomb-maker or makers involved in the Brussels attacks and to identify any links to the bombs used in Paris.
"We will do whatever is necessary to support our friend and ally Belgium in bringing to justice those who are responsible," US president Barack Obama said, ordering American flags lowered to half-mast until Saturday.
Belgium's king and queen said they were "devastated" by the violence, describing the attacks as "odious and cowardly."
After nightfall, Europe's best-known monuments - the Eiffel Tower, the Brandenburg Gate and the Trevi Fountain - were illuminated with Belgium's national colours in a show of solidarity.
Meanwhile, the US military said it had launched an air strike in Yemen against the branch of al Qaida responsible for the attacks in France that killed 12 people at the Charlie Hebdo satirical magazine in January.
A tribal member at the site said about 40 people were killed or wounded in the Brom Maifa district.
Pentagon spokesman Peter Cook said the mountain training camp was being used by more than 70 terrorists belonging to al Qaida in the Arabian Peninsula.
Yemeni security officials and a witness said the air strike hit a former military base that had been taken over by al Qaida militants about 47 miles west of the terror group's stronghold city of Mukalla.
"We continue to assess the results of the operation, but our initial assessment is that dozens of AQAP fighters have been removed from the battlefield," Mr Cook said.
"This strike deals a blow to AQAP's ability to use Yemen as a base for attacks that threaten US persons and it demonstrates our commitment to defeating al Qaida and denying it safe haven."
Yemen has been left fragmented by war pitting Shiite Houthi rebels and military units loyal to a former president against a US-backed, Saudi-led coalition supporting the internationally-recognised government.
A Peruvian woman was identified as one of those killed in the airport bombings.
The country's Foreign Ministery named her as Adelma Tapia Ruiz, 37.
Her brother Fernando Tapia told Peruvian radio station RPP that his sister was at the airport with her Belgian husband Christophe Delcambe and their twin four-year-old daughters Maureen and Alondra, who also have Belgian nationality.
He said Mr Delcambe and the girls were unhurt because they left the area where the explosions occurred moments before the bombs detonated.