It has come up on the margins, but the increasingly violent clashes in Hong Kong have barely registered on the formal agenda of G7 leaders meeting in Biarritz, France.

At least one expert says the crisis is a crucial test for the world's major democracies — one they may be failing.

A Hong Kong police officer fired a gunshot during protests on Sunday, the first time live ammunition has been used since demonstrations broke out.

Water cannons have also been deployed by authorities and protesters have reportedly lobbed bricks.

At least 36 people were arrested Sunday. Dozens were injured on Saturday in a sharp escalation of violence, after a senior Hong Kong official warned China's military could intervene during any civil unrest.

I think it represents what democracies are about - Colin Robertson, former diplomat

The importance of the world's leading liberal democracies presenting a united front on events in the former British colony cannot be understated, said Colin Robertson, a former diplomat and vice-president of the Canadian Global Affairs Institute.

"I think it represents what democracies are about."

Hong Kong, which counts approximately 300,000 Canadian-Chinese citizens, is perhaps the most cosmopolitan city in Asia, and its political autonomy was guaranteed by international covenants.

The potential violation or even the stealth dismantling of its political and economic freedoms would be a major blow, and having G7 leaders lay down a marker in the face of authoritarian threats — veiled or otherwise — is important.

Protesters clash with police during an anti-government rally in Hong Kong's Tsuen Wan district on Sunday. Pro-democracy protesters have continued rallies against a controversial extradition bill since June 9 as the city plunged into crisis following waves of demonstrations and several violent clashes. (Anthony Kwan/Getty Images)

"If we give China a pass, which I believe [U.S. President Donald] Trump would be inclined to do, then I think you begin to wonder," said Robertson.

"We [democracies] are really on our back foot because around the world, we're losing, and we appear to be losing in so many places."

The leader to watch, given his country's long history in Hong Kong, will be newly installed U.K. Prime Minister Boris Johnson, Robertson added.

"Where does he come from on this? I think his inclination might be to just put it under the table."

The issue of Hong Kong was raised at least twice in bilateral discussions Prime Minister Justin Trudeau had with Johnson and Japan's Shinzo Abe.

Canada and the EU issued a joint statement on Hong Kong earlier this month, calling for China to show restraint.

"It is crucial that restraint be exercised, violence rejected and urgent steps taken to de-escalate the situation," said the Aug. 17 statement.

"Fundamental freedoms, including the right of peaceful assembly, and Hong Kong's high degree of autonomy under the 'one-country, two-systems' principle, are enshrined in the [Hong Kong] Basic Law and in international agreements, and must continue to be upheld."

The statement drew a sharp, personal rebuke for Canadian Foreign Affairs Minister Chrystia Freeland from Chinese authorities.

A Canadian official going into the weekend's gathering said there hasn't been much indication from the other countries that they consider Hong Kong a major topic for the leaders beyond where it might fit in an overall discussion about China.

Canada has made its position known on both the unrest in Hong Kong, and the arbitrary detentions of Michael Spavor and Michael Kovrig, and has already been given assurances of support from all of the G7 nations, publicly or privately.