Belgian authorities were investigating Thursday how far the network of attackers who carried out the deadly bombings in Brussels reached, as a state broadcaster reported that a second man likely took part in the subway explosion.
RTBF said it was unclear whether the unidentified man, who was captured on surveillance camera carrying a large bag, was still alive. Prosecutors did not immediately comment on the report.
Khalid El Bakraoui, 27, died while carrying out the suicide bombing, which involved an explosion in the second car of a subway as it was pulling out from a station in central Brussels on Tuesday morning.
The blast was the more deadly of two attacks, including earlier explosions in the Brussels airport departure hall in which two bombers were killed. One of those bombers was El Bakraoui's brother, Ibrahim.
Belgian prosecutors said they found statements from Ibrahim in a rubbish bin near the house where he was picked up by taxi on the morning of the bombings that suggested he was afraid of being caught imminently by police.
Local media reported that the brothers had hidden a surveillance camera outside the house of Belgium's nuclear director, indicating other potential plans that may have been cut short.
A third airport attacker, shown in widely circulated photos pushing a luggage cart in a black bucket hat with a light jacket on, is still being sought by Belgian police.
Authorities are stringing together a complex web of interlacing evidence, with Belgian media reports naming a third suicide bomber as Najim Laachraoui, who was already sought in connection with November's terrorist attacks in Paris.
The key surviving suspect from those attacks, Salah Abdeslam, was captured in Brussels just days before the deadly explosions in the Belgian capital.
Although he was expected to fight an extradition request from France, his lawyer, Sven Mary, said in televised remarks that Abdeslam wants to be sent to the country "as fast as possible."
Abdeslam was due in a Belgian court Thursday, but his case hearing was postponed at the request of his lawyer, who said he needed more time to study the case.
Thirty-one people were killed and 300 injured in the two Brussels attacks, though officials have warned that the casualty numbers are still apt to change. Sixty-one people are in intensive care.
The EU ministers responsible for justice and security will meet in Brussels on Thursday afternoon to "show solidarity with Belgium, discuss the actual state of play in the fight against terrorism and pursue swift completion and implementation of legislation."
EU Home Affairs Commissioner Dimitris Avramopoulos said Wednesday that the emergency meeting would serve to "put ... pressure on everybody to do more."
He criticized the slow progress on new security measures that have been proposed by the European Commission.
"If now is not the time to step up cooperation, then I don't really know when is," Avramopoulos said. "It's beyond time to get serious about security, because safety is also one of the fundamental rights of our citizens."
Belgians are struggling to understand how the attacks could have been carried out by men who were born and raised in the country, where three days of national mourning are under way.
A man who said he knew the brothers and their family told dpa that they seemed like normal, if angry, young men who had recently been released from prison.
"They were not fanatics; not religious fanatics," said Makran Hakim, 49, who used to work as a barber in the Brussels neighbourhoods where the brothers spent time.
A national minute of silence is scheduled to be held across Belgium at 2:30 pm (1330 GMT) in memory of the attacks' victims. A tribute will also be held at 2 pm in the Belgian parliament, due to be attended by King Philippe and Queen Mathilde.