Gibraltar police, in a joint cross-border operation with the Spanish Guardia Civil, arrested two local people on suspicion of money laundering earlier this week.
The suspects, who are husband and wife, have been released on police bail.
The arrests came after officers from the RGP's Money Laundering Unit obtained a warrant and carried out a search of a property, during which they found a very large amount of cash.
They also impounded a £200,000 luxury yacht which was berthed in Gibraltar, and several items of computer equipment.
The couple are believed to have close links with organised crime groups in Spain.