One of the men who carried out the Brussels suicide bombings had been wanted by police in connection with the terrorist attacks in Paris last November, Belgian prosecutors said Thursday.
An international arrest warrant had been issued for Khalid El Bakraoui on December 11, amid suspicions that he had used a false identity to rent a hideout allegedly used by the Paris terrorists in the southern Belgian city of Charleroi.
El Bakraoui, 27, died on Tuesday while helping carry out a suicide bombing at a central Brussels subway station. His brother, 29-year-old Ibrahim El Bakraoui, was one of two suicide bombers who died in an earlier attack at Brussels Airport.
Belgian federal prosecutors said on Wednesday that the brothers both had "a loaded criminal record, not linked to terrorism."
But Belgian authorities have since come under pressure over revelations that Turkey had warned Belgium last year about Ibrahim El Bakraoui being - in President Recep Tayyip Erdogan's words - a "foreign terrorist warrior."
Interior Minister Jan Jambon and Justice Minister Koen Geens both offered to resign, but Prime Minister Charles Michel did not accept.
Jambon told the VTM broadcaster on Thursday that there were a lot of "big questions" and that he only accepted to stay in his post because of the current "war"-like situation.
Geens, meanwhile, pointed in an interview with the VRT broadcaster to the possibility that information was circulated too slowly from Turkey to Belgium, as well as within Belgium.
Tuesday's attacks left at least 31 people dead and 300 injured, while the airport and Maelbeek subway station sustained heavy damage.
Investigators are trying to track down one airport bomber who is believed to still be on the run. They have also been working to piece together how far the network of attackers reached.
The RTBF broadcaster reported on Thursday that a second man likely took part in the attack on the Maelbeek station. RTBF said it was unclear whether the unidentified man, who was captured on surveillance camera carrying a large bag, was still alive.
The newspaper La Derniere Heure released what it said was a sketch of the suspect, but prosecutors said in a statement that the image has "no relevance" in their investigation.
The statement also said that police had searched the Brussels homes of the El Bakraoui brothers on Wednesday, but not found anything.
According to some media reports, 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.
Prosecutors have said that Ibrahim El Bakraoui had suggested that he was afraid of being caught imminently by police in a will that was found on a computer recovered by police from a rubbish bin.
Authorities are stringing together a complex web of interlacing evidence, with Belgian media reports naming one of the deceased airport bombers as Najim Laachraoui, who was already sought in connection with the Paris attacks.
Those attacks had left 130 people dead. A key surviving suspect, 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 on Thursday 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.
Belgians are struggling to understand how the attacks could have been carried out by men who were born and raised in the country.
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.
Belgium is in the midst of marking three days of national mourning. A tribute to the victims was held at the Belgian parliament on Thursday, along with a national minute of silence.
"We will not give in to barbarism," Michel said at the parliament ceremony. "We will not give in to hatred. We stay together, united."
Brussels Airport said Thursday that there will be no passenger flights to or from the airport through Sunday and that passengers are now allowed to retrieve checked-in and hand luggage from some of the planes that were on the tarmac when the terrorist attacks occurred.