Machine-gun toting robbers disguised as cops made off with $50 million worth of diamonds in a spectacular heist on the tarmac at Brussels airport, prosecutors and dealers said on Tuesday.
Monday night's robbery at Zaventem airport was "one of the biggest" ever, said a spokeswoman for the Antwerp World Diamond Centre (AWDC), the global dealers syndicate.
The raid saw a gang of eight "heavily-armed and hooded" thieves pull up on the runway in two black vehicles with blue police-like markings, Brussels prosecutors' spokeswoman Anja Bijnens told a press conference at Zaventem airport.
They opened security barriers and sped towards a Swiss passenger aircraft on the runway where they forced open the cargo hold to reach the rough gems that had already been loaded, she said.
Bijnens said the raiders were "wearing police uniforms" and carrying "machine guns," adding: "They wanted to pass themselves off as cops."
They seized "at least 120 packages," which was only a "partial" haul from the shipment, she said.
Amazingly, "no shots were fired and no-one was injured," Bijnens said of a robbery that was over "within minutes."
She said the thieves made off "at high speed" through the same gap in the security cordon they had opened in front of unsuspecting ground staff and travellers, adding that the passengers on board the plane "saw nothing" and that the aircraft, bound for Zurich, did not leave Brussels.
According to the AWDC, the global diamond business is worth more than $60 billion each year.
Some $200 million worth of stones move in and out of Antwerp every day, the spokeswoman added.
The gems taken here were "rough stones" being transported from Antwerp to Zurich, the AWDC spokeswoman said.
Neither the prosecutor's office nor the AWDC official would give any details as to who the shipment belonged to.
One of the robbers' vehicles was found afterwards "completely burnt out" near the airport, the spokeswoman for the prosecutor's office said.
A specialist Belgian prosecutors unit dealing with organised crime is "pursuing all lines of enquiry," Bijnens said, and is collaborating also with Swiss authorities.
"This was not a random robbery," she stressed. "It was well-prepared -- these were professionals."
Belgian Justice Minister Annemie Turtelboom was on hand at the airport as the investigation gathered pace.
There are more than 4,500 diamond dealers in Antwerp, the hub for a worldwide industry going back at least 500 years, the AWDC said.