Hiring private investigators to crack down on ride-sharing service Uber will create further confusion and uncertainty for the taxi industry, the WA Opposition says.

The ABC revealed yesterday the Department of Transport has issued a tender document seeking a contractor to provide private investigators to ensure Uber was complying with the law.

The State Opposition said the move flew in the face of recent comments by Premier Colin Barnett, who declared the service was here to stay and said his Government would not try to shut it down.

WA Labor's acting transport spokesman Paul Papalia said the Government seemed to be in a state of utter confusion over the matter.

"What we see now is the Transport Minister spending taxpayers' money on three years' worth of tendering for private investigators into Uber, only days after the Premier said he wasn't going to oppose Uber and they are here to stay," he said.

"The Premier has completely contradicted the Transport Minister and then days later we see the Transport Minister again contradicting the Premier.

"You've got to ask, what on earth is the Government's position on Uber?

"The industry deserves some sort of certainty and you're not getting that at the moment."

Mr Papalia questioned how the industry would benefit from the hiring of private investigators.

"What has to happen is the Government has to determine what its position is, and then it needs to respond with either legislation or regulation, or even consideration of compensation for people that have been caught in this position," he said.

"Small business operators and taxi owner/operators have entered this industry under set circumstances and regulation governing that industry imposed by Government and now that entire environment has changed, but the Government has just been dragging its heels to respond."

Uber 'shocked' at news of private investigators

In a statement, an Uber spokeswoman said the company looked forward to speaking with Transport Minister Dean Nalder and the Premier's office to "seek legal clarity around the issue".

"In the light of the Premier's recent comments recognising the positive impact Uber is having in Perth, it is shocking that the Department of Transport has issued a tender for private investigators to target their own citizens looking to earn extra income through ride-sharing," she said.

"Hundreds of thousands of Western Australians are now choosing Uber because it is safe, reliable, affordable and they love having it in their city.

"They do not expect their taxes to be spent stopping a service they want."

Mr Nalder is overseas and was unavailable for comment, but a Department of Transport spokeswoman said in a statement it was only seeking to administer WA's Taxi Act.

"When gathering intelligence or investigating suspected offences ... it is sometimes appropriate to undertake surveillance," she said.

"In a rapidly changing environment of innovation and disruptive technology regulators must also innovate and be creative in their responses."