Former Chinese premier Wen Jiabao has pleaded innocence over claims that his family amassed huge wealth during his decade in power, a Hong Kong columnist said, as Beijing ramps up a much-publicised crackdown on official corruption.

"I have never been involved and would not get involved in one single deal of abusing my power for personal gain because no such gains whatsoever could shake my convictions," Wen said in a letter to Ng Hong-mun, a columnist with the Ming Pao newspaper, a Hong Kong-based Chinese-language daily.

"I want to walk the last journey in this world well. I came to this world with bare hands and I want to leave this world clean," Wen said, according to Ng's column published on Saturday.

Wen's letter dated December 27 follows a 2012 New York Times report that claimed his family controlled assets worth at least $2.7 billion -- a report China vigorously denounced as a smear.

Ng is a Hong Kong-based politician who frequently comments on relationships between Beijing and the semi-autonomous region, which was returned to Chinese rule in 1997.

He is known to have ties to Wen, and a photo taken of both men and their wives after an April 2011 dinner in Beijing was circulated widely in the Hong Kong press.

News of Wen's letter comes amid an escalating campaign by the current Chinese leadership, led by President Xi Jinping, to fight corruption among high-ranking officials, or "tigers", as well as low-level "flies".

Analysts say that while there is little chance that Wen himself would be ensnared in that crackdown, the former premier is under pressure to clear his name following the New York Times investigation.

Recent reports of an official probe into China's former chief of internal security, Zhou Yongkang, a onetime member of the all-powerful Politburo Standing Committee, could have prompted Wen to act, said Willy Lam, a politics specialist at the Chinese University of Hong Kong.

"I think the point of Wen Jiabao's letter... is to pre-empt innuendo and speculation that he might be the next to go, after Zhou Yongkang," Lam said.

"Because of the widespread publicity generated by the New York Times and other reports, there has also been speculation that Wen Jiabao could be the next one to come under the party discipline, if not public prosecution," he added.

He noted that it was "highly unlikely" that Wen himself would be charged, "the major reason being that all this action against top officials is connected with a power struggle within the party".

The New York Times was awarded a Pulitzer Prize for its investigation into the wealth of Chinese leadership but has also had its website blocked in mainland China. Several reporters for the newspaper have also had difficulty obtaining visas to report from China.

Wen stepped down as premier last March after a decade in power and was succeeded by Li Keqiang in the Communist Party's decennial leadership change.