'These were absolute fabrications and vicious attacks,' he said, referring to allegations that he had favoured an in-law's light-bulb business with his plan to encourage the use of energy-saving bulbs, and had intervened in his sister-in-law's claim for compensation for her investment in failed Lehman Brothers minibonds.

'In recent days, there is a worsening trend for these unrestrained attacks, which were totally groundless and designed to weaken public trust in the government,' the chief executive said. Expressing regret at the 'twisting of the facts by individual newspapers', Tsang said: 'I believe the public and any person who has a passion for the freedom of speech will not support this kind of action.'

His remarks followed allegations of favouritism towards his elder son's father-in-law, Anthony Mok Kam-chuen, whose business distributes Philips light bulbs, in his policy address announcement of a voucher plan for energy-saving bulbs.

This was swiftly followed by the disclosure that his sister-in-law received 60 per cent compensation three months before 16 banks offered most other investors compensation for their investments in Lehman-Brothers minibonds.

Tsang has admitted raising the matter with officials but denied exerting pressure to speed up the compensation process.

Over the past two weeks, several Chinese-language newspapers have run daily front-page stories about the allegations, with some comparing him to former Taiwanese president Chen Shui-bian, who was jailed for corruption.

But Tsang yesterday reiterated his earlier stance that encouraging the use of energy-saving bulbs was part of the government's green-policy package, and benefiting his in-law was not his intention. 'It is unfair ... when someone twisted this open and transparent policy to a case of transferring interest.'

Although he has yet to answer key questions - such as why Lam Suk-jing, the wife of his younger businessman brother - received her compensation earlier than most other small investors after seeking assistance from lawmaker Abraham Razack, Tsang dismissed allegations of his involvement as 'totally groundless accusations'.

'I did not know in advance of my relative's demands to the bank for compensation, and I have absolutely not exercised my power to affect the settlement agreement,' he said.

Former security chief Regina Ip Lau Suk-yee, now an independent legislator, said Tsang's counter-attack on the media would not help improve his image.

'It was not a good strategy for Mr Tsang to respond in such a combative tone. Instead of appearing so angry, he should rebuild a co-operative relationship with the media,' she said.

Ip Kwok-him, of the Democratic Alliance for the Betterment and Progress of Hong Kong, said: 'He can't satisfy the public only by expressing his feelings. He should calmly tell people everything about the incident.'

Cheng Yiu-tong was the only Executive Council member to defend Tsang publicly.

'I believe these attacks on Mr Tsang are intolerable in a society under the rule of law,' he said. 'Frankly speaking, there have been repeated attacks on him. Tolerance has reached a limit. I support his hitting back.'

A person familiar with the government position said the chief executive hoped to send the message that media comments should be based on facts.

'There are worrying phenomena among some media. In the past, media stopped targeting a public figure after making reports for one or a few days if they failed to find fresh evidence about him. But the recent negative reports about the chief executive have been lingering for two weeks, even if there was a lack of concrete evidence to support the accusations,' the person said.

The Hong Kong Journalists Association said monitoring the government and public figures was the media's duty, but it would not comment on editorial decisions of individual media organisations.

Cheng Ming-yan, chief editor of Apple Daily, which compared Tsang to Chen Shui-bian on its front page last week, said he had no idea which newspaper Tsang was referring to, adding: 'We have not fabricated anything.'

In a poll conducted by the University of Hong Kong last week, public dissatisfaction in the policy address rose 14 percentage points to 45 per cent, just days after a similar poll was conducted between October 15 and 17. Those who said they were satisfied with the address rose by just 1 point to 20 per cent.

More than 41 per cent of respondents said they were dissatisfied with the policy direction of Tsang, a 7-point increase from the previous poll.

The chief executive said yesterday that he respected such poll findings and the government always reflected on its performance.

Ivan Choy Chi-keung, a Chinese University political scientist, said Tsang's latest move would undermine his popularity.

'The fact that the media could keep the story on the front page for two weeks demonstrated that public mistrust towards Tsang had risen to a new high. But not only has he not recognised this, he has attacked the media.'