The former British riot police officer claims that he executed his first citizen's arrest of an "unlicensed UberX driver" on Thursday.

Mr Howarth has been a hire-car driver for the past decade and frequently uses the standard service from Uber.

Uber is a smartphone app that competes with taxis for customers and requires you to be a licensed hire-car driver and to pay the fees associated with it.

UberX, which launched in Sydney in April, is a controversial low-cost initiative from Uber that allows anyone with a vehicle to register as a hire car driver.

Legally, hire car or taxi drivers must have specific licences in order to operate.

Mr Howarth claims that UberX drivers are "operating outside the law," and that they are undermining the work of licensed Uber drivers.

On Thursday, he decided to take the law into his own hands.

"I ordered an UberX car and got in the vehicle," Mr Howarth said.

"I asked the driver if he had the proper insurance, a public passenger vehicle authority or if he had paid his plate fee.

"When he admitted to driving a hire car illegally, I informed him I was a private citizen and that I was affecting a citizen's arrest. I told him to take me to Newtown police station.

"When I took him in with me to the police station, they got a bit confused."

When police questioned his right to arrest someone, Mr Howarth recited section 352 of the Crimes Act of 1900.

"A person (other than a police officer) may, without a warrant, arrest a person if they are in the act of committing an offence under any act or statutory instrument," he said.

The law relating to a citizen's arrest now falls under Section 100 of the Law Enforcement (Powers and Responsibilities) Act 2002.

Newtown police said that the UberX driver had the correct credentials.

"Police checks revealed that the driver was driving a registered vehicle and was properly licensed, meaning no further police action was taken."

They would not comment on the legality of citizen's arrests. 

Amazing scenes outside Newtown Court House, Sydney as first of many UberX drivers being arrested. @bengrubb pic.twitter.com/UaHgZkXX2H — Arresting Uber (@arrestinguber) October 16, 2014

Uber has labelled the arrest a "stunt".

"It was an attempted publicity stunt," an Uber spokesman in Sydney said. "I'm sure we would have heard if any Uber partners had been arrested, but we have not."

Mr Howarth claims that he will continue to arrest an UberX driver every day until the NSW government clamps down on the hire care service.

Mr Howarth alleges that "Uber is contravening the legal system, blatantly avoiding paying GST and other relevant taxes".

Thursday's arrest was borne out of frustration with the government's inaction over UberX and its drivers skirting the law, Mr Howarth said.

Uber claims that its low-cost UberX service will offer customers up to a 20 per cent discount on standard hire car fees. But not requiring hire car drivers to be properly licensed is in breach of the passenger transport act. The maximum penalty is a $110,000 fine.

The NSW Minister for Transport, Gladys Berejiklian, warned that hire car drivers who were not licensed appropriately would face the consequences.

"It is currently illegal for drivers in NSW to participate in what we call 'ride-sharing' activities like UberX," she said.

"The Roads and Maritime Service has already issued several fines of thousands of dollars for those breaking the law.

"My main concern at this stage is the safety of customers."

Mr Howarth said that he had now started a national campaign, and that he had "hundreds of licensed hire car drivers ready to enforce citizen's arrests of UberX drivers".

The Taxi Council of NSW said that it did not condone any citizen's arrests, but that it did have concerns over Uber's business model.

Uber has not responded to requests for comment about the legality of their operations.