Lawyers for relatives of Chinese Premier Wen Jiabao have hit back at an "untrue" New York Times article which alleged the family has accumulated vast wealth, a report said Sunday.

Hong Kong's South China Morning Post, which printed what it said was a statement from the lawyers, said it was the first time the family of a top Chinese leader has issued a rebuttal of a foreign media report.

Friday's New York Times (NYT) article came at an especially sensitive time, as the Communist Party strives to clean house before a pivotal handover of power next month.

Detailing a string of deals, the NYT said many relatives of the government's number two -- a self-styled man of the people -- had become "extraordinarily wealthy" during his years in office.

Investments by Wen's son, wife and others spanning the banking, jewellery and telecom sectors were worth at least $2.7 billion according to an analysis of company and regulatory filings from 1992-2012, it said.

Wen's 90-year-old mother owned a stake valued at $120 million in 2007 in the Ping An insurance giant, according to the US newspaper.

The allegations come as a particular embarrassment for Wen, who is expected to step down as premier next March. He is the standard-bearer of the party's reformist wing and has campaigned against rampant corruption.

The South China Morning Post reproduced the statement from two lawyers, Bai Tao and Wang Weidong, rejecting aspects of the NYT report. China's foreign ministry has denounced the article as a smear campaign.

The lawyers denied that Wen's mother Yang Zhiyun ever held a US$120 million investment in Ping An Insurance. She had "never had other income or property" except for her government salary and pension.

"The so-called 'hidden riches' of Wen Jiabao's family members in The New York Times' report does not exist," the statement said.

The lawyers said they would continue to "make clarifications regarding other untrue reports" by the newspaper and reserved the right to hold it "legally responsible".

Their statement said Premier Wen "has never played any role in the business activities of his family members" and had not allowed those activities to influence his policies.

The lawyers could not be reached by AFP for comment Sunday.

The NYT report found no indication Wen had intervened on behalf of family members and said he himself did not appear to have accumulated assets. It did not suggest that any of the family's business activities were illegal.

The NYT said on its website it was standing by the story.

It noted that while the lawyers disputed that Wen's mother had held assets, it did not address the article's calculation that the family had controlled assets worth at least $2.7 billion.