Panama law firm Mossack Fonseca specialised in setting up offshore companies © Getty

UK authorities charged by the prime minister with forming a “task force” in response to the Panama Papers leak have cautioned that the scandal over offshore tax dealings may not translate into prosecutions.

Mark Steward, head of enforcement at the Financial Conduct Authority, warned on Wednesday that the headlines generated by the leak were “quite different from prosecutions — the two don’t necessarily go together”. The FCA had not yet seen the 11m documents from Mossack Fonseca, the Panamian law firm at the centre of the scandal, added Mr Steward.

“This is very difficult territory. No one should underestimate the task. Most [authorities] are set up to do a domestic job, not to do things internationally. Collaboration is easier said than done.”

The FCA, the Serious Fraud Office and HM Revenue & Customs were instructed by the prime minister to look at cases resulting from the Panama Papers leak. Speaking at the same London conference, David Green, the head of the SFO, said the files “are being, and will be, accessed”.

Britain’s financial authorities were caught on the back foot last year over another story about collusion over tax evasion involving HSBC’s private Swiss bank, with parliamentarians calling their response “pathetic”.

This time they are moving faster. The FCA — which has said financial crime and money-laundering are among its priorities for the year — has already given banks and other organisations a deadline of last week to complete initial reviews into potential links to Mossack Fonseca any companies formed by the firm, or to other individuals and entities named in the Panama Papers.

HSBC, Coutts, Rothschild, UBS and Credit Suisse are among groups that used Mossack Fonseca to set up thousands of offshore concerns for their clients over 40 years, according to data uncovered by the International Consortium of Investigative Journalists.

The ensuing scandal cost Iceland’s prime minister his job and embarrassed Mr Cameron— who once promised to remove the “cloak of secrecy” from offshore tax havens — after it emerged that he profited from his father’s own offshore fund.

The prime minister is due to host an international anti-corruption summit next month. As well as setting up the task force, the UK wants to introduce a corporate criminal offence of failing to prevent tax evasion. A similar offence already exists for bribery.

Mr Green has long pushed for an extension of that law beyond bribery across all financial crime. While there was broad cross-party support for such a move 18 months ago, the government quietly announced it was dropping the plans in September; part of a series of moves that have sparked concern among opposition and backbench MPs over whether tough post-crisis reform is being abandoned since the Conservatives’ victory at last year’s election.

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