Officers have also uncovered several works of Renaissance art, a huge haul of valuable jewellery and a gun.

Counterfeit currency, passports, chequebooks and credit cards were found stashed in secure boxes at three London businesses.

Armed police are guarding the addresses in Park Lane, Hampstead and Edgware as officers remove valuables and take them to a secret secure storage facility.

Two directors of the safe-keeping company have been arrested on suspicion of money laundering offences.

Officers from the Metropolitan Police's specialist crime directorate raided seven addresses on Monday as part of Operation Rize. It was the first swoop of its kind against criminals using this type of secure storage to hide their ill-gotten gains.

Detectives believe some of the UK's top villains used the company to hide the proceeds from almost every type of crime. Police said they have been inundated with phone calls from concerned box owners as they try and sort legitimate property from criminal proceeds.

More than 7,000 safety deposit boxes of all shapes and sizes, rented for as little as £100 a year, were seized during the operation.

Police are using specialist tools to open them and examine the contents and recover forensic evidence.

Anyone who is concerned that police have seized their property should call 0800 030 4613.