Chinese President Xi Jinping's family features in the massive leak of confidential data showing how the world's elites deploy tax havens to shield their wealth.
Xi's brother-in-law Deng Jiagui set up two British Virgin Islands companies in 2009, according to a report by the International Consortium of Investigative Journalists and German daily Sueddeutsche Zeitung released late on Sunday.
Deng and family members of at least eight current and former members of China's politburo standing committee set up offshore companies through Mossack Fonseca, a Panama-based law firm with offices in more than 35 countries including China, the report said.
China's central bank has taken measures over the past year to reduce the transfer of money overseas by wealthy Chinese.
Almost half of wealthy individuals on mainland China have "earmarked" nearly a third of their assets for overseas investment, according to an investigation by the Financial Times in August.
A grandchild of Jia Qinglin, a top-ranking Chinese Communist official, and former Chinese premier Li Peng's daughter Li Xiaolin were identified in the Panama leaks.
Representatives of the Chinese leaders did not respond to requests for comment, ICIJ said.
Sueddeutsche Zeitung said on Sunday that the cache includes 4.8 million emails and nearly 2.5 million documents and is several times larger than a previous cache of offshore data published by WikiLeaks in 2013.
State prosecutors in Panama launched an investigation following the leak, authorities said.
