The British government sought on Monday to deflect any criticism of Prime Minister David Cameron over his late father's inclusion on a list of clients using a law firm in the tax haven of Panama and said it would investigate the leaked data.
Cameron's father, Ian, and members of his Conservative Party were among the tens of thousands of rich and famous people named in a leak of documents from Panama-based Mossack Fonseca which showed how clients had evaded tax and laundered money.
The documents, which emerged in an investigation published on Sunday by the International Consortium of Investigative Journalists (ICIJ), are a blow to Cameron, a critic of tax evasion and tax avoidance.
In 2012, British media reported that Cameron's father ran a network of offshore investment funds to help build the family fortune. There is no suggestion he did anything illegal.
Asked on Monday whether she could confirm that no family money was still invested in those funds, Cameron's spokeswoman said: "That is a private matter."
Britain's HM Revenue and Customs said it had asked for a copy of the leaked data so it could examine the information.
"We have already received a great deal of information on offshore companies, including in Panama, from a wide range of sources, which is currently the subject of intensive investigation," Jennie Granger, director general of enforcement and compliance at HM Revenue and Customs, said in a statement.
"We have asked the ICIJ to share the leaked data that they have obtained with us. We will closely examine this data and will act on it swiftly and appropriately."
Opposition Labour finance spokesman John McDonnell said the Panama Papers showed Cameron had failed to end tax secrecy and crack down on offshore schemes and called for "real action".
But the government said Britain had brought in more than 2 billion pounds ($2.84 billion) from offshore tax evaders since Cameron took office in 2010 and that Britain was "leading the pack internationally" on tackling tax evasion and avoidance.
Since Britain made the issue a central plank of its G8 presidency in 2013, 90 countries have signed up to the automatic exchange of tax information, Cameron's spokeswoman said.
She said Britain was pushing its overseas territories and crown dependencies, many of which are tax havens, to create public registers of who owns companies in their jurisdictions. Britain's own such register will go live in June.
Asked if Britain would legislate to force territories such as the Cayman Islands and the British Virgin Islands to publish the information, she said: "The prime minister has made clear that should they fail to do so he rules absolutely nothing out."