Banks and financial firms have been told to hand over any information about their dealings with the law firm at the centre of the Panama Papers to the UK’s Financial Conduct Authority by a week on Friday.

The City regulator had written to major financial firms on Monday, as the details of the accounts handled by the law firm Mossack Fonseca began to emerge, to ask what information banks held about any dealings with it and gave them 10 days to provide any details they may have.

Around 20 firms have received the correspondence from the FCA, which is responsible for regulating the City and has made tackling money laundering and financial crime one of its seven priorities for this year.

The 15 April deadline for information about dealings with Mossack Fonseca is contained in the letter, which also asks what action they are taking as a result of the release of the 11.5m files from the Panama-based law firm.

“Beyond 15 April we will require updates on any significant issues or relationships identified and a full response, detailing your findings, when your investigation is concluded,” the letter said, according to the Financial Times.