Brussels attacks come just four days after capture of Paris terror suspect Salah Abdeslam
It is believed Brussels explosions could be in retaliation for the arrest of Abdeslam
The series of attacks in Brussels this morning comes just four days after Salah Abdeslam, a key suspect in the Paris attacks, was captured at a house.
Abdeslam, suspected as a logistician in the attacks that killed 130 people, was arrested on Friday after a four-month manhunt in the same neighbourhood in Brussels where he grew up.
It is believed the two explosions at Brussels Zaventem airport and the explosion at a Metro station near the neighbourhood of Maelbeek area of Brussels could be in retaliation for the capture and arrest of Abdeslam.
Authorities say they do not know the "exact path" taken by Salah Abdeslam since the attacks in Paris on November 13 and they are not sure of who he has been in contact with.
Belgian prosecutor Frederic Van Leeuw told reporters at a news conference in Brussels that investigators hope to find out the details of Abdeslam's actions between the November 13 attacks and his arrest, "if he decides to tell us".
Abdeslam, 26, a French citizen who grew up in Brussels' Molenbeek neighbourhood, slipped through police fingers on multiple occasions, including the day after the attacks. He was interviewed three times on Saturday, the day after his capture - once by prosecutors and twice by an investigating judge - and "wasn't in great shape" because he had been shot in the leg by police during his capture, Mr Van Leeuw said.
He was also described as being "worth his weight in gold".
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Belgian prosecutors also appealed to the public Monday for information about a man who allegedly travelled to Hungary last year with the top suspect in the Paris attacks.
The federal prosecutor's office said in a statement they are seeking details about 24-year-old Najim Laachraoui, who is said to have travelled to Syria in February 2013.
It said Laachraoui was checked by guards at the Austria-Hungary border while driving in a Mercedes with Abdeslam and one other person.
Laachraoui is said to have rented a house under the name of Soufiane Kayal in the Belgian town of Auvelais that was allegedly used as a safe house. Prosecutors said traces of his DNA were found there.
Laachraoui is "someone who must explain himself," the prosecutor said, stressing that "clues" do not amount to proof.
Investigators have been working on numerous pieces of the puzzle in the many-tentacled Paris attacks case and are now faced with the fact that there may have been a retaliation attack in Belgium this morning.
"We are far from putting the puzzle together," said Mr Van Leeuw.
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Anti-terrorism prosecutors in Belgium and France have worked non-stop on hundreds of cases - 325 cases last year in Belgium and near 60 new cases so far this year, Mr Van Leeuw said.
His French counterpart, Francois Molins, who was also at the news conference, said his team has 244 anti-terror cases in progress concerning 772 individuals either charged or sought.
"(It's clear) we have a general threat," Mr Van Leeuw said.
Abdeslam has a court hearing tomorrow. France has requested his extradition but Abdeslam's lawyer says his client will fight the request.