The jihadists behind the Paris and Brussels terror attacks had planned to kidnap well-known figures in a bid to trade them for their brethren jailed in Belgium.
Investigators came to the conclusion after discovering a recorded conversation in a laptop found in a dustbin in the Brussels neighbourhood of Schaerbeek, from where the perpetrators of the March 22 attack on the Belgian capital's airport had left, public broadcasters RTBF and VRT reported yesterday.
The conversation was between an Islamic State group jihadist in Syria and Ibrahim El Bakraoui and Najim Laachraoui, who blew themselves up at the airport, and Khalid El Bakraoui, a suicide bomber who attacked the Maelbeek metro station.
The investigators have identified the jihadist in Syria as Osama Atar, a Belgian-Moroccan veteran extremist in his 30s who served time in US prisons in Iraq, RTBF said.
The three men, who had been hiding in Brussels, planned several terrorist acts including kidnapping "one or two" personalities to demand the "liberation of brothers and sisters" jailed in Belgium, including Mehdi Nemmouche, who killed four people during a May 2014 attack on the Jewish Museum in Brussels.
"It will be a great victory" for IS, Lachraoui was quoted as saying.
Belgian prosecutors refused to comment on the reports when contacted by AFP.
The men finally did not carry out the kidnapping plan but killed 32 people and injured hundreds more in their attacks on the airport and the metro station.