Seven people have been held on suspicion of involvement in a €75 million ($80 million) diamond heist in 2005 at Amsterdam’s Schiphol airport, police in the Netherlands say.

The seven Dutch nationals, five men and two women, were arrested in Amsterdam and Valencia in Spain.

The armed gang, disguised as airport workers, stole the diamonds as they were about to be put onto a plane.

Some of the stones were recovered from a getaway car but stones worth an estimated €40 million are still missing.

According to correspondents, the theft was one of the world’s biggest ever jewellery heists.

The diamonds and other jewellery were stolen in a high security area of the airport after the thieves forced their way into a KLM armored car.

The seven were detained in raids on January 20 and 21 on suspicion of robbery and money laundering.

The diamonds were about to be flown to Antwerp, Europe’s diamond capital, when the robbers struck.