Brussels bomb attacks suspect Najim Laachraoui is believed to have been an accomplice of Paris attacks plotter Salah Abdeslam and may be an Islamic State bombmaker.
Laachraoui is one of three suspects in Tuesday's attacks on Zaventem airport and a metro station that killed at least 34 people and injured hundreds more.
On Wednesday morning, Brussels media announced he had been arrested before withdrawing the claim.
The 25-year-old, who is also known as Soufiane Kayal, was pictured on CCTV at the airport wearing a distinctive bucket hat and a white jacket shortly before the explosions.
Laachraoui was seen pushing a trolley alongside what was initially thought to be brothers Khalid and Brahim el-Bakraoui. However, authorities now believe Khalid el-Bakraoui was in fact on the metro that was targeted, and that only Brahim el-Bakraoui was involved in the airport attack.
The brothers are believed to have died - one at the airport, the other on the metro - after detonating explosives, while Laachraoui is still at large.
According to DH.be, he was already wanted by authorities in connection with the November 13 attacks on Paris that claimed over 130 lives.
Laachraoui is suspected of being a bombmaker and an associate of Abdeslam who was arrested last week in Brussels.
His DNA was reportedly found on explosives used in the Paris attacks.
According to the New York Times his DNA was also found at two homes in Belgium that were searched by authorities in the months after the Paris attacks.
During one of the searches police found traces of TATP, which the Times claimed has become the signature explosive for the Islamic State.
The group have already claimed responsibility for the Brussels bombing.
Authorities are said to have renewed their search efforts for Laachraoui last week after Abdeslam told police he and others were planning further attacks.
According to Belgian media reports, Laachraoui was born in Morocco and raised in Brussels.
The Times reported that he had studied electromechanical engineering at a Catholic high school in Schaerbeek. CNN further claimed that Laachraoui travelled to Syria in 2013 and had been there as recently as September 2015 with Abdeslam.
During that trip he was said to have used his false name of Soufiane Kayal at the border between Hungary and Austria.
DH.be reported that Khalid and Brahim el-Bakraoui had also been sought following the police raids that led to Abdeslam's arrest. The brothers had escaped during an earlier shootout,
Belgian federal prosecutors said investigators found an explosive device containing nails, “chemical products” and an ISIS flag during a raid after the Brussels bombings, the Associated Press reported.
Authorities were led to the apartment by a taxi driver who drove the three men to the airport, without knowing of their plan.
The taxi driver contacted police after the bombing.