Millions of documents obtained from a Panama-based law firm reveal links to 72 current or former heads of state, such as Russian leader Vladimir Putin, according to media reports.

The leak of some 11 million documents came from Mossack Foneseca, naming 23 individuals with sanctions imposed on them for backing regimes in Zimbabwe, Russia, North Korea, Iran and Syria.

Mossack Fonseca has denied wrongdoing and said offshore companies of the sort it creates are offered for a range of legitimate purposes. According to its own website, the firm describes itself as "a leading international company with a presence in over 40 countries and with close to 40 years of history in the legal industry. We operate through our own and representative offices. All our offices maintain the highest due diligence standards that comply with all international laws and regulations."

A report by the BBC quoted the International Consortium of Investigative Journalists, a Washington DC-based organisation that has been involved in obtaining information from other offshore financial centres, including Guernsey and Switzerland.

Responding to BBC claims about the use, or misuse, of Panama structures to conceal wealth, Mossack Fonseca said: "Your allegations that we provide structures supposedly designed to hide the identity of the real owners, are completely unsupported and false. We do not provide beneficiary services to deceive banks. It is difficult, not to say impossible, not to provide banks with the identity of final beneficiaries and the origin of funds."

Data also shows that Icelandic Prime Minister Sigmundur Gunnlaugsson had an undeclared interest in his country's bailed-out banks. Gunnlaugsson has been accused of hiding millions of dollars of investments in his country's banks behind a secretive offshore company. Gunnlaugsson and his wife bought offshore company Wintris in 2007, the BBC report said.

A number of other jurisdictions have seen leaks of data about persons with accounts there, such as Switzerland, the British Virgin Islands, and Guernsey. As has been noted before, the holding of such accounts is not evidence of wrongdoing although politicians are particularly vulnerable to the charge of hypocrisy, because of how many countries have sought to squeeze offshore centres in recent years.

Panama is no longer on the Financial Action Task Force's list of countries that have been identified as having strategic AML deficiencies.

HM Revenue and Customs has said it is prepared to follow up allegations of money laundering and tax avoidance in the wake of the revelations.

HMRC's director general of enforcement and compliance, Jennie Grainger, was quoted by Sky News as saying: "HMRC can confirm that 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 an intensive investigation."

Tax authorities in New Zealand and Australia are also reportedly examining data for possible leads.

Other reports said the data pointed to a link between a member of global football body FIFA's ethics committee and a Uruguayan football official who was arrested last year as part of a US investigation into corruption.

"The release of the Panama Papers is the latest in a series of leaks in what is a very 21st century problem for institutions who are required to hold their client’s data confidentially. In an age where huge quantities of data can be transferred at the press of a button, and where the international political climate is resolutely hostile to those who are perceived to be evading tax, money laundering or breaching sanctions, those who believe that their confidentiality is assured are at increased risk of discovery," Jessica Parker, partner at financial crime and regulatory law firm Corker Binning, said.

Fiona Fernie, head of tax investigations at international law firm Pinsent Masons said: “Any information which suggests UK-based individuals are involved in tax evasion through Panamanian structures is likely to lead to a burst of investigative activity by the Revenue - it is likely they will look closely at anyone named in the data. The Revenue now has a good amount of experience dealing with data leaks, and is likely to respond quickly and efficiently. As with the HSBC Geneva data leak, anyone named in the list with UK tax affairs is likely to receive a letter and face follow-up investigation. Panama is a popular location for this kind of structure- especially for those who are internationally mobile, and those who spend a lot of time in the Americas. There is likely to be a wealth of data for the Revenue to look at."

 Varonis vice president of strategy and market development, David Gibson, said the vast leak also raises questions about company's security practices. Varonis is a US-based firm.

"Email servers tend to be one of the largest troves of valuable information. If you were spying on a company, the CEO’s mailbox would be a pretty fantastic place to see what was going on. One of the security challenges with email is that the most valuable mailboxes tend to be the least secured. This is because executives and law-firm partners often have assistants and other people that get access to their mailboxes – some even have banks of admins that all have access for long periods of time. Another security challenge with email is that mailbox activity is rarely logged or analyzed, making it very difficult to spot abuse or theft. Lastly, Microsoft Exchange has “public folders” where a lot of sensitive information can pile up, and a lot of companies don’t pay much attention to securing. If an assistant’s account gets compromised through phishing or password stealing, or if an assistant turns out to be acting maliciously, the contents of the executive’s mailbox can easily be compromised without detection."