Close relatives of seven current or former Chinese leaders have been found to have links to offshore firms.
Documents leaked from Panama name family members of the Chinese President, Xi Jinping, and two other members of China's elite Standing Committee, Zhang Gaoli and Liu Yunshan.
Relatives of the three men are listed as directors or shareholders in firms located in known tax havens.
The Chinese government has not responded to requests for comment.
The names appeared in a mass leak of files from Panamanian law firm Mossack Fonseca.
Chinese state media are blocking reports of the families' offshore dealings, and the news is being censored on Chinese social media outlets.
It is not illegal for Chinese citizens to set up offshore companies. However, China's Communist officials are discouraged from profiting from their ruling positions and their family members are not supposed to profit from their ties, according to the party's constitution.
Panama Papers - tax havens of the rich and powerful exposed
- Eleven million documents held by the Panama-based law firm Mossack Fonseca have been passed to German newspaper Sueddeutsche Zeitung, which then shared them with the International Consortium of Investigative Journalists. BBC Panorama and UK newspaper the Guardian are among 107 media organisations in 76 countries which have been analysing the documents. The BBC does not know the identity of the source
- They show how the company has helped clients launder money, dodge sanctions and evade tax
- Mossack Fonseca says it has operated beyond reproach for 40 years and never been accused or charged with criminal wrong-doing
- Tricks of the trade: How assets are hidden and taxes evaded
- Panama Papers: Full coverage; follow reaction on Twitter using #PanamaPapers; in the BBC News app, follow the tag "Panama Papers"
- Watch Panorama at 19:30 on BBC One on Monday, 4 April, or catch up later on the BBC iPlayer (UK viewers only)
More than 300,000 party officials were punished last year under an ongoing anti-corruption campaign, orchestrated by President Xi.
The BBC's East Asia Editor, Celia Hatton, says the news that he and two other top leaders have close relatives with ties to offshore companies comes as an embarrassment to the Chinese leadership.
All three men have in-laws who are listed as directors or shareholders in companies located in known tax havens, including the British Virgin Islands.
It is widely known that many of China's elite families have succeeded in the business world and their wealth is well documented.
However, the leaked files from Mossack Fonseca divulge how much of that wealth is managed overseas, in opaque corporate structures that until now remained hidden from public view.