"An app that is not from a recognised taxi booking company offers customers no protection and opens them up to fraud, physical assault or worse," he explained.
"Because these apps are outside the system, no one has a record of the booking and you can't even guarantee that the car is a real taxi."
Mr Wash said that due to the lack of safeguards anyone can register as a taxi and respond to a booking, something he has proved by registering himself on the app 'goCatch' as a driver, despite having no taxi license.
"It is entirely possible for someone with wrong intentions to pick up passengers who may be alone or in a vulnerable situation.
"If you book a cab through one of these unauthorised apps, you should ask yourself who is behind the wheel of the car turning up."
Mr Wash is also concerned about the risk to drivers. "Drivers could be lured to remote areas with no record of the call or details of the person they are scheduled to pick up.
He said the Queensland taxi industry is currently well-regulated and taxi travel is extremely safe for the public.
"Every driver is police-checked daily and there are checks and balances to ensure our customers are safe, but these unauthorised smartphone apps sit outside these safety guidelines."
Mr Wash said authorised apps from legitimate taxi companies will still protect customers.
"Most taxi companies have apps and these all meet the government requirements, so I urge the public to use them and avoid third-party unauthorised apps," he said.
For a list of Queensland taxi companies with authorised apps see www.tcq.org.au