A taxi association and an "anti-Uber activist" who places drivers under citizen arrest have teamed up in an attempt to shut down the popular ride-sharing app UberX.

While drivers using the app have faced fines for working without accreditation, now the company itself has become a legal target.

Uber sought an injunction in Sydney's Supreme Court to stop Russell Howarth, a former taxi driver, from intimidating, harassing, threatening or arresting UberX drivers.

On Friday, Mr Howarth launched a cross-claim that the Australian Taxi Drivers Association said it was funding. It calls for an injunction against "any smartphone software application that allows or aids Unaccredited Persons to carry on a service providing the carriage of passengers for a fare".

The cross-claim accused Uber of breaching section 37 of the Passenger Transport Act (1990), which relates to the use of private hire vehicles.

Mr Howarth said he was confident his claim would succeed and that he had "absolute faith" in the judiciary. "The only way to deal with Uber effectively is to have them injuncted," he said. "The industry is rapidly losing faith in the political process."

In July, the NSW government launched an independent taskforce to look into regulating the ride-sharing industry. Roads and Maritime Services was forced to drop charges against 24 UberX drivers in late July, blaming "evidentiary issues".

Mr Howarth's lawyer, David Taylor, said the UberX platform was "permitting the unlicensed and unregulated to do work". Mr Taylor said he believed the cross-claim was the first Australian legal action against Uber as a company as opposed to individual drivers.

The company said on Monday it did nothing to breach the Passenger Transport Act.

"All cases against Uber driver partners in New South Wales have been dropped," a spokesman said.

Uber said Mr Howarth had no legal right to bring his claim and that he was already under a temporary injunction.

In court documents, Uber alleged Mr Howarth conducted 13 "citizen arrests" of UberX drivers between October and June.

"The defendant instructed the UberX driver partners to take him to various destinations," the company said. "Upon arriving at the destinations, the defendant ... with the use of force or threatened use of force detained each of the UberX driver partners."

Uber said Mr Howarth had assaulted, intimidated and falsely imprisoned drivers in the process, damaging Uber's reputation and costing it customers. ​

Mr Howarth is not shy about conducting arrests. He runs a website called Arresting Uber and has invited media organisations, including Fairfax Media, to film him in action.

But in a defence claim, Mr Howarth described Uber's allegations as "vague, embarrassing and likely to be struck out". He also said the company had no legal standing to sue on behalf of its drivers.

The legal fight comes as Uber prepares for a September 1 case against the Australian Taxation Office over the application of GST.

Uber will argue for an exemption because "ride-sourcing drivers do not supply taxi travel". The company announced on Friday it would raise prices 10 per cent in the meantime.

The case against Mr Howarth returns to court before Justice John Sackar​ on October 6.