Last main Brussels and Paris suspects held, threat remains

But while pleased with the performance of Belgium's hitherto much criticized security services, Prime Minister Charles Michel warned that further threats to Europe were still live: "We are positive about the recent developments in the investigation," he told a news conference. "But we know we have to stay alert."

Mohamed Abrini, believed to have helped prepare the Nov. 13 Paris attacks, was seized on a Brussels street on April 8. Prosecutors said he confessed to being the "man in the hat" seen at the city's airport with two suicide bombers on March 22. That further confirmed close links between the two operations.

In a statement, prosecutors also said they had confirmed that a second fugitive seized separately on April 8 in Brussels was indeed the man seen with a third suicide bomber on March 22 who struck shortly afterward on the Belgian's capital's metro.

Identified by officials as Osama K. and widely named in local media as a 28-year-old Swede called Osama Krayem, this man was also filmed buying bags used to carry the Brussels bombs and his fingerprints were found, like Abrini's, in an apartment used as a bomb factory and safe house for the Brussels attackers.

Also like Abrini, Krayem was identified as associating with the prime surviving Paris suspect Salah Abdeslam in the days and weeks before the November bloodbath that left 130 people dead.

As with other suspects in both Paris and Brussels attacks, police believe Krayem returned from fighting with Islamic State in Syria via refugee boats last summer reaching Greek islands.