Journalists in Hong Kong Thursday slammed a government bid to restrict access to information about company directors, after a series of investigative reports into the hidden wealth of Chinese officials.

Under the proposals put forward by the financial services and treasury bureau, corporate directors could apply to have their residential address and full identity card or passport numbers blocked from public view.

Such information can presently be accessed with a small fee, and has been used by reporters to help unravel a web of secret assets showing the true wealth of China's ruling elite and their families.

"We believe that the ability of foreign correspondents and journalists to legally access information about individuals and their companies is vital to our role of reporting on issues of public interest," the Foreign Correspondents' Club of Hong Kong said in a letter addressed to the city's leader Leung Chun-ying.

"We call on the government to withdraw this amendment and to maintain its support for the free flow of information in Hong Kong."

The former British colony, which reverted to Chinese rule in 1997, maintains a semi-autonomous status with guarantees of civil liberties -- including press freedom -- not seen on mainland China.

The proposal comes amid concern over meddling by Beijing in the city's affairs, and after a number of reports focusing on the wealth and assets of China's ruling elite grabbed worldwide headlines.

In June last year, financial newswire Bloomberg used publicly available records to compile a list of investments made by the extended family of Xi Jinping, just months before he became head of the ruling Communist Party.

The agency said the investments totalled US$376 million.

The New York Times said in October that financial records showed outgoing premier Wen Jiabao's relatives had control of assets worth at least $2.7 billion, a report Beijing branded as a smear.

Bloomberg said it used Hong Kong and Chinese identity card numbers from corporate filings to chart business ties among Chinese officials and their heirs, while the New York Times also used such information from Hong Kong.

Access to the websites of both Bloomberg and New York Times in China has since been blocked.

A large number of Chinese companies are listed in Hong Kong, a financial hub that acts as a gateway for international firms seeking to tap the booming Chinese market.

"It's a damage to the free flow of information, which is the bloodline of investigative reporting," Mak Yin-ting, the chairwoman of the Hong Kong Journalists Association, told AFP.

Without the ability to access the ID numbers of company directors it would be difficult to confirm a person's identity, she added. Dozens of people might share the same name with the same Chinese characters.

But the financial services and treasury bureau said in a statement the amendment was needed "to strike a balance between the right of the public to information and the protection of privacy".

It added that under the proposal the public would still be able to access a director's correspondence address as well as three of the seven digits of their ID number.

"This should be enough for the public and the media to identify the persons concerned," the statement said.

The government aims for the new law to come into effect in the first quarter of 2014.