The former chief editor of a Hong Kong newspaper whose removal from his post triggered protests over press freedom and Beijing's influence was critically ill after being attacked with a cleaver Wednesday.

Kevin Lau would undergo extensive surgery on his lungs and legs but his life was not in danger, Ronald Chiu, the head of the Hong Kong News Executives Association, told reporters after a conversation with hospital doctors.

Lau, former chief editor of the liberal Ming Pao newspaper, was hacked in broad daylight by two men who escaped on a motorbike in the Chai Wan district.

Lau, who was known for hard-hitting political investigations before being removed from his post in January, was confronted when he got out of his car.

"One of them alighted from the motorcycle and used a chopper to attack the victim," police spokesman Simon Kwan said outside the hospital.

"He suffered three wounds, one in his back and two in his legs," Kwan said, adding that the wound to his back was deep.

A government spokesman said Lau was in a critical condition.

Hong Kong lawmaker Regina Ip told AFP the men "chopped him so hard that people could see his internal organs", citing a conversation with Lau's wife Vivian Chan.

Lau was replaced by an editor from Malaysia seen as pro-Beijing, prompting protests by staff who feared an attempt to stifle the paper's investigative reporting.

Among Ming Pao's past reports were several on the death of Chinese dissident Li Wangyang.

Wednesday's wounding follows several less serious attacks on journalists in the semi-autonomous Chinese territory, and comes three days after a march in support of press freedom.

Over two weeks in June last year there were multiple attacks against employees of Apple Daily, a popular tabloid critical of Beijing, according to the New York-based Committee to Protect Journalists.

The same month Chen Ping, a publisher of a magazine known for its outspoken coverage of mainland issues, was beaten up, it said.

Media groups urged police to pursue Lau's attackers.

"We strongly condemn violence and urge the police to take action," Hong Kong Journalists Association chairman Sham Yee-lan told AFP.

The Foreign Correspondents' Club voiced shock at the incident.

"Hong Kong's reputation as a free and international city will suffer if such crimes go unsolved and unpunished," it said in a statement.

Critics said Lau's sidelining was politically motivated as the city takes part in a debate about its future political system, almost 17 years after the handover from British rule, and as concerns mount that Beijing is seeking to tighten control.

Under a deal between London and Beijing, Hong Kong is guaranteed freedom of speech among other liberties that China's mainland residents are denied.

But earlier this month two reports from international media watchdogs said self-censorship was becoming commonplace.

Vibrant press under pressure

Compared to the tightly controlled state press on China's mainland, Hong Kong's newsstands and networks offer a noisy jungle of competing outlets from across the political spectrum.

But the Committee to Protect Journalists said this month that media freedom was "at a low point".

It cited self-censorship among reporters, financial and physical threats against the media and legislative steps that could hinder investigative reporting.

Paris-based Reporters Without Borders also said Hong Kong's media independence was "now in jeopardy" as China flexed its muscles to stifle critical coverage.

The day the reports were released, radio host Li Wei-ling, who was known for her biting commentary against Beijing and the Hong Kong government, said she had been sacked from her station.

Top Hong Kong officials condemned Wednesday's attack.

"The government and I are extremely concerned and outraged about the attack on Mr Lau this morning and we strongly condemn this savage act," Beijing-backed Chief Executive C.Y. Leung said in a statement.

"Hong Kong is a lawful society and we will not tolerate violence."

Chief Secretary Carrie Lam told reporters she was "shocked and saddened" by the assault.

"Hong Kong is a city with rule of law. All of society should condemn violence," she said. -- AFP