Belgian, French and Swiss police have recovered part of a spectacular $50-million diamond heist in gems and cash and made multiple arrests in a vast cross-border operation, Belgian officials said Wednesday.

A suspected member of the eight-man gang who nabbed the diamonds on a Belgian airport tarmac just under three months ago was picked up in France on Tuesday as Swiss police made six arrests and seized some of the missing diamonds, a spokesman for the Brussels prosecutor's office said.

"The probe led to a big police operation yesterday," spokesman Jean-Marc Meilleur told a news conference.

In early morning raids Wednesday involving some 200 officers, Belgian police made 24 arrests and "recovered big amounts of cash", Meilleur added.

The February 18 robbery at Zaventem airport was at the time described as "one of the biggest" ever by the Antwerp World Diamond Centre (AWDC), the global dealers' syndicate.

The brazen heist was carried out by eight men who pulled up on a runway where a Swiss passenger aircraft was about to take off and forced open the cargo hold to reach gems already loaded onto the plane.

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