A report by the International Federation of Journalists warned Monday of "intervention behind the scenes" of Hong Kong's media as fears grow over press freedoms and interference from Beijing.

It is the second report this month to flag up concerns over media censorship and manipulation as well as physical assaults on journalists in a city which prides itself on freedom of expression, compared with severely restricted reporting in mainland China.

"As well as highlighting the pressure by political forces, the IFJ reminds the business sectors of the mainland and Hong Kong that a free and independent press plays an important role in the business environment," it said in a statement.

"Press freedom is a human right and the media must be able to perform their professional duties without fear or intimidation."

Tensions remain high in Hong Kong after more than two months of mass protests for fully free leadership elections ended in December, with no concessions on reform.

The IFJ report presented at Hong Kong's Foreign Correspondents' Club is based on the first-person accounts of three journalists, all of whom used pen names.

A Hong Kong journalist using the name Lam Hei described 2014 as a "watershed" for the city's media and said it had "abandoned editorial independence".

Sensitivity towards advertisers and "unusually frequent" contact between Hong Kong officials and media managers were among pressures publications faced, Lam's account said.

The journalist said that interference from Beijing was "raw and undisguised" with officials based in Hong Kong putting pressure on reporters during the protests.

"Most of the media did not offer resistance... the Hong Kong media have already half-knelt," the journalist said.

The report comes less than two weeks after another from US literary and human rights group PEN American Center which said the media in Hong Kong was at "increasing risk", with physical assaults and cyber attacks among the threats.

A British colony until 1997, Hong Kong is ruled under a "one country, two systems" deal that allows it far greater civil liberties than those enjoyed on the Chinese mainland, including freedom of speech and the right to protest.

But there are growing concerns that those long-held freedoms are being eroded.

A number of high-profile media figures have been attacked, with the latest two weeks ago, when the home and office of pro-democracy media tycoon Jimmy Lai were firebombed. Lai and his outspoken newspaper Apple Daily have been repeatedly targeted.

The former editor of liberal newspaper Ming Pao, Kevin Lau, is still recovering after being attacked with a cleaver in the street in broad daylight last February.

Two Chinese journalists who contributed to the IFJ report also told of tightening controls on the already strictly censored media on the mainland, describing the situation as "the darkest days" for 15 years. (+++++)