The UK's financial regulator has handed banks and financial firms a deadline of next week to check if they have links to a law firm at the centre of the Panama Papers leak.
The Financial Conduct Authority (FCA) has told 20 banks and businesses that they have until April 15 to investigate whether they have ties to Mossack Fonseca or firms which are managed by the company.
It comes after a leak of more than 11 million documents from the law firm in Panama sparked allegations of money laundering and tax evasion by high-profile figures across the globe.
The FCA has called on banks to reveal what action they are taking after the Panama Papers leak revealed more than 500 banks, including their subsidiaries and branches, registered nearly 15,600 shell companies with Mossack Fonseca.
HSBC, Credit Suisse and the Royal Bank of Scotland-owned Coutts Trustees denied claims earlier this week that they were helping clients avoid tax by using complex offshore structures.
In a statement, the FCA said: "The FCA has written to a number of firms about this issue, including those on our Systematic Anti-Money Laundering Programme, and we are working closely with a number of other agencies who are also looking at this.
"As part of our responsibility to ensure the integrity of the UK financial markets we require all authorised firms to have systems and controls in place to mitigate the risk that they might be used to commit financial crime."
The FCA pinpointed financial crime and anti-money laundering as a key focus for the organisation when it announced its annual business plan earlier this week.
The plan states: "It is imperative that the UK financial system has appropriate safeguards to prevent financial crime.
"At the same time, it is important we ensure that financial crime regimes are proportionate and operate efficiently and that any unintended consequences of regulation are minimised."