Several senior Hong Kong police officials feel caught between a rock and a hard place as the city's chief executive Carrie Lam tries to ram through contentious extradition laws that have triggered violent clashes between police and protesters.

Key points: Over 1 million Hongkongers protested against a proposed extradition bill on Sunday

Over 1 million Hongkongers protested against a proposed extradition bill on Sunday The bill would allow Beijing to try the city's citizens and foreigners on the mainland

The bill would allow Beijing to try the city's citizens and foreigners on the mainland Critics of the bill fear it will dissolve freedoms the city was promised under "one country, two systems" rule

Police fired tear gas, bean bag rounds and rubber bullets at young protesters who gathered this week around the Chinese-ruled city's legislature and government headquarters in the tens of thousands.

The clashes wounded 22 police and more than 60 protesters, as demonstrators advanced toward the legislature, hurling bricks, iron poles and sticks, while barging their way forward with metal barricades.

"We are definitely restrained and we wouldn't indiscriminately use weapons," police chief Stephen Lo told reporters a day after the clashes, describing them as a "riot".

Riot police formed a blockade as protesters marched near Hong Kong's Legislative Council. ( AP: Kin Cheung )

"We were facing tens of thousands of protesters. The pressure was very great."

The protesters demand that Ms Lam — once described as Beijing's "puppet" — scrap controversial amendments to an extradition bill that would allow individuals, including foreigners passing through Hong Kong, to be extradited to mainland China.

Hong Kong returned from British to Chinese rule in 1997 under a "one country, two systems" deal guaranteeing it special autonomy, including freedom of assembly, a free press and an independent judiciary, which was ratified in 1984.

But many have accused Beijing of extensive meddling in the city's affairs, with the extradition bill a further example.

The business community, lawyers, judges, rights groups and foreign governments have called on Ms Lam — who says the initiative was hers and not Beijing's — to scrap the bill.

But her refusal to do so has incensed the public, who lack confidence in both China's legal system and assurances that safeguards introduced into the bill will ensure individuals get a fair trial on the mainland.

One in seven Hongkongers marched in protest

Protesters have voiced their distrust of mainland China's opaque legal system. ( ABC News: Brant Cumming )

Over 1 million people, or one in seven people in the city, marched on Sunday against the bill.

Less than a day later, however, a stern-faced Ms Lam told reporters she would not back down.

Some senior police officers say Ms Lam's refusal to heed public opinion is sowing resentment in the force, which was already battered by accusations of police brutality during the 2014 pro-democracy "Umbrella" civil disobedience movement.

"There are a significant number that blame her for this crisis," said a senior law enforcement officer in a command position.

"It's madness."

He said the demands of the protesters weren't unreasonable, given an inherent mistrust of mainland China's legal system.

"There's definitely a feeling that we're trapped in the middle," said a senior police officer who declined to be named as he was not authorised to speak to the media.

"We can't solve this. The protesters can't solve this. But Carrie can."

'They didn't deal with the situation rationally'

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 22 seconds 1 m 22 s Hong Kong protesters have accused the police of violently responding to their demonstrations.

At the same press conference by Hong Kong's police chief, a group of more than 20 photo-journalists donned hard hats and gas masks in a symbolic protest against what they considered to be the excessive use of force by police during the unrest.

"Some police were out of control," said Leung Pang-wai, 28, a photographer for HK01 newspaper who wore a gas mask during the press conference.

"They shot at us and they didn't deal with the situation rationally."

Senior police officers, however, defended the use of force to deal with much more violent protesters than during the 2014 demonstrations, when tens of thousands occupied roads around the legislature and government headquarters for 79 days.

The protesters this time, unified for a very specific goal — to prevent a policy seen as an existential threat to Hong Kong's unique global position — have pledged not to back down.

Police used pepper spray numerous times against protesters during the unrest. ( AP: Vincent Yu )

A hardcore element, numbering in the tens of thousands, has not shied away from violence, while being highly organised and tech-savvy, using encrypted phone apps like Telegram to mobilise swiftly through multiple group chats, and more strategically, with less risk of police infiltration.

"Telegram is a big breakthrough from the old traditional strategies," said Jason Chan, a 22-year-old protester.

"Since there were no leaders in this movement, Telegram facilitates the communication across protesters by allowing different channels or groups to set up and thereby unite the people."

Another senior law enforcement officer acknowledged greater risks going forward.

"The protesters are a lot more determined this time," he said.

"The violence will keep escalating if the government doesn't back down."

Steve Vickers, a former commander of the police's Criminal Intelligence Bureau who now runs a risk consultancy, said in a report that there was a risk of further violence.

"An unfortunate polarisation has occurred, where demonstrators perceive the police to be the enemy [rather than the government], and many junior police officers see both the media and protesters as the main protagonists."

ABC/Reuters