The prosecutor also linked Laachraoui to November's Paris carnage in which 130 people died, saying his DNA was found on a suicide vest and a piece of cloth discovered at the Bataclan concert hall where 90 people were killed.
Police also found his DNA on a bomb at the Stade de France, a statement said.
CCTV footage showed three bombers at Brussels airport on Tuesday, with Laachraoui and Ibrahim El Bakraoui now being named as the two who blew themselves up there.
The police have launched a massive search for this third man.
The prosecutor's office also confirmed that Laachraoui had previously used the false identity of Soufiane Kayal.
Key Paris attacks suspect Salah Abdeslam went to the Hungarian capital Budapest in September and on his return was stopped by police on the Austrian border with two men -- Soufiane Kayal, as he was then known, and Samir Bouzid.
Laachraoui, 24, went to Syria in early 2013.
He was a good student with an immaculate disciplinary record at a Brussels Catholic school, and friends and family remember a bright easy-going kid who liked to play frisbee and football.
"I don't understand how anyone can be brainwashed so quickly," Brice Vanhee, a college friend from his first year electro-mechanical engineering course in 2012, said on Facebook.
"How can you switch sides and blow yourself up when you used to play frisbee tournaments every weekend? I don't get it!"
A picture on Vanhee's page shows a group of eight students including Laachraoui smiling at the camera.
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
