Details claiming to reveal how little income tax US billionaires pay have been leaked to an news website.
ProPublica says it has seen the tax returns of some of the world's richest people, including Jeff Bezos, Elon Musk and Warren Buffett.
The website alleges Amazon's Mr Bezos paid no tax in 2007 and 2011, while Tesla's Mr Musk paid nothing in 2018.
A White House spokeswoman called the leak "illegal", and the FBI and tax authorities are investigating.
ProPublica said it was analysing what it called a "vast trove of Internal Revenue Service data" on the taxes of the billionaires, and would release further details over coming weeks.