Affluent Chinese have discovered a safer place than under the mattress to keep their valuables - bank vaults.

Bank safe-deposit services have grown ever more popular as individuals accumulate wealth and seek safe storage.

Bank safe-deposit services have grown ever more popular as individuals accumulate wealth and seek safe storage. [CFP]

Businessman Yang Liming believes banks are a safer place than home to keep valuables like jewelry, gold bullion, bank-deposit books, wealth-management contracts and property-ownership certificates.

"Bank vaults are underground and guarded," said Yang.

"And banks are a lot tougher to break into than an ordinary home," he said.

Safe-deposit boxes are usually arranged in underground vaults, where gaining access requires customers to undergo a fingerprint check, verify their identity and provide a password to gain access to their box.

In addition, two keys are required to open each box, with one held by the customer and the other by the bank.

Rental fees vary according to box size and range from several hundred to several thousand yuan a year.

The minimum box size is small enough to store an apple, but just right for a small jewelry collection.

There are also larger options to house bigger items like paintings, antiques or other works of art.