Embattled Hong Kong leadership candidate Henry Tang said Wednesday he believed he could still win this weekend's election despite reports that Beijing has switched its support to his rival.

Tang, a wealthy businessman and the city's former chief secretary, was believed to have Beijing's backing until a series of personal scandals and gaffes destroyed his standing with the general public.

The South China Morning Post daily cited unnamed sources close to Beijing saying the central government had started to privately lobby for Leung Chun-ying, Tang's chief opponent ahead of Sunday's vote.

"Every candidate has a chance to win or lose," Tang, 59, said when asked to comment on the report.

"My target is on March 25. I will work harder to gain the support from the people in the next four days," he told reporters.

A 1,200-member electoral committee packed with mainly pro-Beijing business and professional elites will choose a replacement for outgoing Chief Executive Donald Tsang, whose term expires in June.

Ordinary Hong Kongers do not have the right to elect their leader, but have made their opinion known through approval ratings showing Leung, 57, with a hefty lead over Tang and pro-democracy candidate Albert Ho.

Pro-Beijing Liberal Party chairman James Tien was quoted by the Post as saying he believed Leung had a better than 50 percent chance of winning, after Beijing started to make its intentions clear to committee members.

Despite Leung's higher popularity with ordinary citizens over his promises to boost social welfare and public housing, he is facing a parliament inquiry for conflict of interest in a government property project a decade ago.

He also faces claims of links to triad figures and of being a secret member of the Chinese Communist Party -- a claim he has repeatedly denied.

Veteran pro-democracy lawmaker Emily Lau said Beijing's reported bid to canvass support for Leung showed the central authorities' "blatant interference" in Hong Kong's political affairs.

"It seriously undermines the 'one country, two systems' model because the central government officials are directly issuing orders to the Hong Kong government and election committee members on what to do," she said.

"This election is nothing but a farce because they (Beijing) are pulling strings from behind the scene and treating the election committee members as puppets," the Democratic Party acting chairwoman told AFP.

Mainland leaders, who are in the midst of their own once-in-a-decade leadership struggle, have not openly backed any candidate.

But some analysts took Premier Wen Jiabao's comments last week that the southern financial hub's next chief would have the support of the "vast majority" of the people as a sign that Leung was now Beijing's man.

Hong Kong Baptist University political scientist Michael DeGolyer, who is on the electoral committee and supports Ho, said "for the first time" Beijing officials were paying close attention to what Hong Kong people wanted.

"Beijing officials have said repeatedly that public opinion matters more, that it needs to be listened to," he told AFP.

Pro-democracy groups meanwhile are lobbying the public to hit the streets on Sunday to protest against the "small circle" electoral system which they see as tilted in favour of China-backed tycoons.

Hong Kong reverted to Chinese control from British rule in 1997, with a semi-autonomous status that guarantees broad social freedoms under limited democracy.