Heavily armed robbers disguised as cops made off with $50 million (37 million euros) worth of diamonds in a spectacular heist on the tarmac at Brussels airport, prosecutors and diamond dealers said Tuesday.
The Monday night robbery at Zaventem airport just before 8 pm (1900 GMT) 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 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.
They forced open security barriers and sped towards a Swiss passenger aircraft about to take off on the runway, forcing open the cargo hold to reach gems that had already been loaded, she said.
Bijnens said the thieves 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.
The Swiss air company said the plane was on a regular flight operated by its partner Helvetic Airways.
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 "included rough stones as well as cut diamonds from Antwerep that were being transported to Zurich," the AWDC spokeswoman said.
"It is worrying that something like this can take place at the airport, that an armed gang can get to the tarmac," said the AWDC spokeswoman.
Neither the prosecutor's office nor the AWDC official would give any details as to whom the shipment belonged. The prosecutor's office said the packages contained mainly diamonds.
The AWDC said the haul was worth $50 million dollars.
One of the 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.