HONG KONG (REUTERS) - Thousands of people in Hong Kong joined an evening protest and marched to major foreign consulates on Wednesday (June 26), urging leaders gathering for this week's Group of 20 (G-20) summit to back their demand to scrap a much criticised extradition Bill.

Holding placards with messages such as "Please liberate Hong Kong", the demonstrators, some wearing masks, marched to consulates of major economies represented at the summit, including the host nation Japan, as well as Britain, Canada, Russia, the United States and the European Union.

"This is the first time so many march to so many consulates to express a single view," said one of the organisers of the march, who gave only his surname, Lau.

Millions have protested in recent weeks against the Bill that would allow individuals, including foreigners, to be extradited to mainland China to face trial in courts controlled by its ruling Communist Party.

Hong Kong's Beijing-appointed leader Carrie Lam eventually caved after some of the worst violence seen in decades on the city's streets, with police firing tear gas and rubber bullets.

But she stopped short of protesters' demands to scrap the Bill altogether, saying it would be suspended indefinitely.

The day culminated in several thousand, mostly young activists, surrounding police headquarters, using metal barricades to blockade entrances. Many donned helmets, masks and goggles, as they cursed Hong Kong's police chief for what they say was a brutal clampdown on some protests in recent weeks.

They also spray-painted and pelted eggs at the building, while occupying nearby roads.

"It's hard to ask people to come out again. So once we are out, we won't retreat," said Mr Joe Yeung, one of the activists.

Since Hong Kong returned to Chinese rule in 1997, it has been governed under a "one country, two systems" formula that allows it freedoms not enjoyed in mainland China, including the liberty to protest and an independent judiciary.

But many accuse China of increased meddling over the years, by obstructing democratic reform, interfering with elections, suppressing young activists, as well as being behind the disappearance of five Hong Kong-based booksellers who specialised in works critical of Chinese leaders.

'BACK HONG KONG'

Protesters earlier handed a petition to the US consulate asking President Donald Trump to "back Hong Kong at the G-20 Summit", where he is due to meet Chinese President Xi Jinping to try to defuse trade tension.

They urged Mr Trump to back a full withdrawal of the Bill and an independent inquiry into the actions of Hong Kong police against protesters.

They also marched to the British consulate, where a man held up a sign reading: "Free HK from China colonisation."

Britain's Foreign Secretary Jeremy Hunt told Parliament on Tuesday that London would ban sales of tear gas to Hong Kong and called for an independent inquiry into the recent violence, a gesture welcomed by some in the crowd.

In Beijing, foreign ministry spokesman Geng Shuang urged Britain not to interfere in China's internal affairs.

"Britain has repeatedly made irresponsible remarks and flagrantly interfered with regard to Hong Kong," he told a daily briefing. "China expresses its strong dissatisfaction and resolute opposition to this."

At the evening gathering on the edge of the Central financial district, thousands of activists - many wearing black - spoke, sang and urged G-20 leaders to defend Hong Kong's rights, holding up a giant banner with the words "Free Hong Kong. Democracy Now".

Raising the extradition saga at the summit could embarrass Mr Xi at a delicate time of rising trade tension with the US, and further pressure Hong Kong's leader amid reports that Beijing has doubts about Mrs Lam's capabilities.

Assistant Foreign Minister Zhang Jun has said China would not allow discussion of Hong Kong at the summit.

But many remained defiant.

"Hong Kong has been standing at the frontline of authoritarianism and autocracy. It's important that we are united," said veteran democrat Lee Cheuk Yan.

In a crowdfunding campaign, Hong Kong activists raised more than HK$5 million (S$866,000) to take out newspaper ads in major foreign media during the summit.

Some Hong Kong activists have also journeyed to Osaka, where the summit will be held.