A rally participant wearing a Guy Fawkes mask attends a human rights rally in Hong Kong on 10 December 2019, the day after the the sixth-month anniversary of a movement that has upended the semi-autonomous Chinese hub's reputation for stability and blanketed its streets with unprecedented scenes of political violence. (AFP)

An international panel of experts hired to advise Hong Kong’s police watchdog over its handling of huge pro-democracy protests announced Wednesday they were quitting, in a major setback for the city’s pro-Beijing government.

The move came a month after a leaked statement from the group revealed they felt the police watchdog was not equipped to carry out a proper investigation, and suggested a fully independent inquiry would be better suited.

On Wednesday, the panel said talks with the Independent Police Complaints Commission had made no headway since that leak.

“As a result, the IEP (Independent Expert Panel) has taken the decision to formally stand aside from its role,” the statement said.

The experts also restated the criticisms it had of the police watchdog it was hired to assess.

“We ultimately concluded that a crucial shortfall was evident in the powers, capacity and independent investigative capability of IPCC,” the experts said.

One of the core demands of protesters — alongside fully free elections — is an inquiry into the police, who have been left to battle black-clad activists for six months and are now loathed by significant chunks of the deeply polarized population.

But both chief executive Carrie Lam and the police have repeatedly rejected those calls.

The panel was announced in September and was chaired by Sir Dennis O’Connor, who was tasked by the British government to write a report on the police after the 2011 London riots.

It included current or former police watchdog chiefs from Canada, Australia and New Zealand, and a British specialist on crowd behaviour.

But their frank assessment was not welcomed by Anthony Neoh, the IPCC’s head.

Earlier this month he gave an interview to a mainland Chinese media outlet rebuking the panel, saying they “do not understand Hong Kong’s situation”.

The IPCC is due to release an interim report on the police reaction to the protests early next year.

But critics say the body lacks adequate investigatory powers, is stacked with pro-establishment figures and has been toothless when it comes to holding the police to account.

The watchdog can only handle complaints forwarded by the police themselves and it cannot subpoena documents or compel witnesses to testify.

Such limitations, the expert panel said, do not “begin to meet the standards citizens of Hong Kong would likely require of a police watchdog operating in a society that values freedoms and rights”.

Monday marked the six-month anniversary of the protests, which were initially sparked by a now-abandoned attempt to allow extraditions to mainland China but have since morphed into a popular revolt against Beijing’s rule.

The last three weeks have seen a rare lull in the violence and vandalism after pro-democracy parties won a landslide in local council elections.

On Sunday, an estimated 800,000 people marched peacefully through the city’s streets Sunday.

An end to violence is something Lam has insisted must be a precursor to meaningful dialogue.

But Lam has shown no sign she is willing to budge, leading to fears clashes could resume.

In her weekly press conference on Tuesday she dismissed protesters’ demands once more as she announced plans to go to Beijing this weekend where she is expected to meet with Chinese leader Xi Jinping.

China has publicly thrown its support behind both Lam and the city’s police, even as their approval ratings take a hammering.