Bai Tao of the Junhe Law Office and Wang Weidong of the Grandall Law Firm, both representing Wen's family, termed the New York Times report as untrue.
In a statement published by Hong Kong media groups, they said they had been "entrusted by the family members of Wen Jiabao" but did not specify which relatives do they represent.
"The so-called 'hidden riches' of Wen Jiabao's family members in the New York Times' report do not exist," the statement said.
"Some of Wen Jiabao's family members have not engaged in business activities. Some were engaged in business activities, but they did not carry out any illegal business activity. They do not hold shares of any companies," the Hong Kong-based media groups quoted the statement as saying.
Wen's 90-year-old mother Yang Zhiyun -- who, the NYT report alleged, had accumulated a lot of wealth, including USD 120 million investment in a large Chinese financial company -- never had any income or property beyond her salary and pension, the statement said.
"Wen Jiabao has never played any role in the business activities of his family members, still less has he allowed his family members' business activities to have any influence on his formulation and execution of policies," it said.
The NYT had alleged in its report that in many cases the names of family members were "hidden behind layers of partnerships and investment vehicles involving friends, work colleagues and business partners".
The lawyers' statement said "other relatives of Wen Jiabao and the 'friends' and 'colleagues' of those relatives are responsible for all their own business activities."
"We will continue to make clarifications regarding untrue reports by the New York Times, and reserve the right to hold it legally responsible," it said.
The NYT, however, said it stood by its story. Eileen Murphy, a spokeswoman for the newspaper, wrote in an email published by the newspaper itself, "We are standing by our story, which we are incredibly proud of and which is an example of the quality investigative journalism The Times is known for."
It was significant that Wen's family chose to rebut the NYT through the Hong Kong law firms, while the story on the US newspaper's website was totally blocked on the mainland. The Chinese Foreign Ministry earlier dismissed the report as a "smear" campaign driven by ulterior motives.
The NYT story comes at a time when 70-year-old Wen, known to be very amiable and simple, is set to retire after a ten- year stint in power, along with other leaders of the ruling CPC. The new leadership would be selected by the ruling Communist Party Congress to be held here on Nov 8.
The Chinese leadership is sensitive to allegations of wealth accumulation as it grapples with the growing rich-poor gap in the country, arising out of the three decades of economic reforms.
A similar report alleging accumulation of wealth by Vice President Xi Jinping, who is tipped to succeed President Hu Jintao, was dismissed by the Foreign Ministry earlier.