Prime Minister David Cameron said he has "no shares, no offshore trusts, no offshore funds" after questions were raised about his family's tax affairs following the data leak known as the Panama Papers.

And former Banbury MP Sir Tony Baldry defended his record after a company he chaired appeared in the documents.

The paperwork revealed efforts by the rich to hide their assets after they were named in relation to investments set up by Panamanian law firm Mossack Fonseca.

More than 11 million documents have been shared with The Guardian, prompting Shadow chancellor John McDonnell to demand an investigation by HM Revenue and Customs.

Sir Tony, who stood down as Conservative MP for Banbury at the last election after serving the constituency for more than 30 years, was a director of Westminster Oil Ltd, a British Virgin Islands company, from 2007 to 2012.

Speaking on a business trip to Namibia in south west Africa, Sir Tony said: "On transparency, as soon as Westminster Oil was registered in the BVI, the names and addresses of the directors, including myself, were publicly recorded in the BVI equivalent of Companies House. This has been publicly available for eight years.

"As soon as I became a director of Westminster Oil I registered that fact with the Register of Members' Financial Interests in the House of Commons.

"I put the fact on my personal CV, on my website, and it was even in my entry in Who's Who - no one could have been more publicly accountable and transparent."

On the issue of tax avoidance, Sir Tony added that the directors' fees, along with other income, were declared to HM Revenue and Customs.

Labour demanded an independent investigation into the tax affairs of those implicated by the records, which includes details about the Prime Minister's dead father, Ian Cameron.

During a visit to Birmingham Mr Cameron said the information should be used to ensure that companies and individuals are paying the tax they should, but sidestepped calls for a probe.

He said: "In terms of my own financial affairs, I own no shares.

"I have a salary as Prime Minister and I have some savings, which I get some interest from, and I have a house, which we used to live in, which we now let out while we are living in Downing Street and that's all I have.

"I own no shares, no offshore trusts, no offshore funds, nothing like that."