The Queen's private estate has been found to have millions of pounds invested in offshore tax havens, according to reports.
A vast tranche of leaked financial documents, dubbed the Paradise Papers, have been analysed by media organisations, including the BBC and The Guardian.
It is alleged that the Duchy of Lancaster, which handles the Queen's investments, has held funds in the Cayman Islands and Bermuda.
Around £10 million of the Queen's private cash is said to have been tied up in offshore portfolios, the BBC reports.
There is nothing to suggest that any investments are illegal, the broadcaster added.
Around 13.4 million files are said to have been involved in the leak, which comes one year after the disclosure of the Panama Papers sent shockwaves through the world of business.
Two offshore service providers are said to be the source of the material, along with the company registries of 19 tax havens.
First obtained by the German newspaper Suddeutsche Zeitung, the documents have reportedly been analysed by almost 100 media organisations.
The International Consortium of Investigative Journalists oversaw the project, it is claimed.
Hundreds of individuals and companies reportedly have their overseas tax affairs laid bare in the papers.
US President Donald Trump's commerce secretary, Wilbur Ross, is allegedly shown to have cash in a shipping company which deals with Russian leader Vladimir Putin's son-in-law.
The Russian firm navigator, in which the offshore investments are reportedly held, has a partnership with Sibur, a gas company co-owned by Kirill Shamalov, who is married to Mr Putin's daughter.
The Paradise Papers allegedly reveal that several major global companies have been exploiting offshore schemes to avoid tax.
Labour leader Jeremy Corbyn said the disclosure "proves" that "there's one rule for the super-rich and another for the rest when it comes to paying tax."
Shadow chancellor John McDonnell added: "These are deeply worrying revelations. Despite all the Government's claims of cracking down on tax dodgers, this evidence confirms that tax avoidance is clearly continuing on an industrial scale.
"Either the Prime Minister or the Chancellor needs to explain how this scandalous behaviour has been allowed to go on unaddressed for so long and what action is to be taken now."