The perpetrator named by Turkish officials as Ibrahim El Bakraoui, one of the Brussels airport attackers who already had a string of criminal convictions and was known to Belgian police.
"We informed the Brussels Embassy of the deportation process of the attacker with a note on July 14, 2015. However, the Belgians released the attacker despite his deportation," Erdoğan said.
Later Thursday, in a statement from the Belgian Federal prosecutor, it emerged that an European arrest warrant had been issued for Khalid el Bakraoui back in December for his role in the Paris attacks.
The comments come as Belgium's authorities scramble to find a fourth man suspected of involvement in the bombings and potentially more terror suspects that could have assisted the bombers.
The attacks have increased pressures on European officials to strengthen anti-terrorism measures in the 28-country bloc, not an easy task as the region deals with an influx of refugees fleeing mainly from civil war in Syria. The EU has a deal with Turkey to halt the influx of migrants but the latest attacks have muddied an already complex dynamic between the EU and its neighbor, which straddles Europe and the Middle East.
Erdogan added that "despite our warnings that this person was a foreign terrorist fighter, Belgium could not establish any links with terrorism" which meant he could walk free. It's not the first time that Turkey has deported suspected terrorists. One of the suicide bombers in the Paris attacks last November had been deported to Belgium from Turkey last year.