Hong Kong protest leader Jimmy Sham attacked by hammer-wielding assailants

Hong Kong protest leader Jimmy Sham has been attacked by hammer-wielding assailants, with pictures on social media showing the young man lying in a pool of his own blood.

Sham, who leads the Civil Human Rights Front (CHRF), was taken to hospital after the attack on Thursday (NZ time), the BBC reports.

Protests have overwhelmed the region since July, with protesters fighting China's influence in the area.

The CHRF said Sham was attacked by five hammer-wielding men in the Mong Kok district of the Kowloon peninsula.

It's the second time he's been attacked after protests began. The last time he was attacked, police charged three suspects, including a 15-year-old boy over the incident, the South China Morning Post reports.

The CHRF said the attack was from pro-Government supporters, who are believed to have also attacked other protesters recently.

"It is not hard to link this incident to a spreading political terror in order to threaten and inhibit the legitimate exercise of natural and legal rights," it said in a statement.

Amnesty International is calling on the authorities to launch an investigation to find who attacked Sham.

"Jimmy Sham was left bleeding on the street and has been hospitalised with head injuries. Even in the context of increasing attacks on activists, this incident is shocking in its brutality," said the head of the rights group's East Asia regional office, Joshua Rosenzwei.

Sham's attack won't put the CHRF off protesting though, the BBC reports it's already applied for a police permit to hold a new march on Sunday.