A cancer patient who left his wallet in Kmart returned to find an employee had cut up all of his cards, citing "store policy".

Glenn Darby, 46, was shopping at the store in Busselton, Western Australia last Wednesday night when he made the mistake. He returned the next day to find employees had not handed his wallet to police.

"The lady said to me, 'You're not going to be happy'. I asked why's that, and she said, 'We had to cut up all your cards, it's store policy'," Mr Darby told Nine News on Friday. "It just seemed aggressive to me, cutting like that. It was bizarre."

Glenn Darby left his wallet in Kmart. (Photo / Nine News)

Not only were both of his bank cards, his Medicare card and a $100 fuel voucher from the Cancer Council destroyed, but also his medical alert card. The bricklayer and father of four was recently diagnosed with a rare oesophagus cancer and needs the number on the card handy, news.com.au reports.

"I ring the number to say what do I do or I need help," he told Nine News. "If my chemo port comes out, it goes everywhere. It's like poison coming out everywhere and interrupts my treatment, and I need it to beat this."

(Photo / Nine News)

Kmart has apologised for the incident. "We deeply regret and sincerely apologise for the incident that occurred in our Busselton store," q spokeswoman said.

"Kmart do have a lost property policy in place for stores, which does not involve the destruction of all personal cards, as has occurred in this situation. This was an unfortunate mistake, and we apologise for the inconvenience caused. We are working with this customer directly to rectify the situation."

(Photo / Nine News)

Mr Darby has been contacted for comment.

According to Luke Cubis, chief executive of lost property software platform It'sFound, the case highlights how many Australian organisations are unaware of the laws around handling lost property.

"The law states that you must manage property in line with how that person would want it handled and stored — it's called 'tort of conversion' — and the finder must make all reasonable attempts to find the owner before destroying the property," Mr Cubis said in a statement.

"If lost property is not managed correctly, staff and organisations can be prosecuted. Kmart isn't alone in having outdated or not best-practice processes. The fact is, Glenn Darby was the legal owner of the property, not Kmart."

It'sFound, a subscription service that launched in 2015, is currently used by hundreds of venues around the world. According to Mr Cubis, the average person loses 190 items in their lifetime worth about $6000.