A Reuters report published earlier this month shone light on a Moldovan "Laundromat" probe into an alleged Russian-led money laundering scheme, in which $22.3 billion passed through Moldova using Russian shell companies and fictitious loans from offshore companies based in Britain in 2011-2014.

The Organized Crime and Corruption Reporting Project (OCCRP), an East European media network, and Russian newspaper Novaya Gazeta have also shared documents and data with the Guardian newspaper and media partners about the alleged involvement of British banks.

British lawmakers tabled an urgent parliamentary question after newspaper reports said that UK banks including HSBC (>> HSBC Holdings plc), the Royal Bank of Scotland (>> Royal Bank of Scotland Group plc), Coutts and Standard Chartered (>> Standard Chartered PLC) were named as being among those that did not turn away suspicious money transfers.

"The Financial Conduct Authority (FCA) and the National Crime Agency (NCA) ... will investigate closely whether recent information from the Guardian newspaper regarding money laundering from Russia, or indeed any other media source, would allow the progression of an investigation," Simon Kirby, the 'City' minister responsible for financial services, said in parliament on Tuesday.

"What is important is that if these allegations are correct, if they present any new information, that both the NCA and the FCA act on it appropriately," added Kirby, responding to a question raised by the opposition Labour Party.

The FCA, tasked with ensuring that financial services companies have adequate, proportionate and efficient safeguards to prevent them being used for financial crime, said it would investigate any evidence that it received.

The NCA said the case involved a number of UK-established companies and that, according to current information, the bank accounts involved were almost entirely held in non-UK jurisdictions. It said the money therefore did not "generally" move through the UK's financial system.

"The NCA remains willing to consider any formal request for assistance from the Moldovan authorities in connection with their investigation, and will consider whether information provided by the Guardian or other media sources would allow the progression of an investigation," it said in a statement.

According to data compiled by the OCCRP and published by the Guardian, HSBC (>> HSBC Holdings plc) saw $545 million routed through its UK and foreign branches.

HSBC is still subject to a five-year deferred prosecution agreement made in 2012 with U.S. authorities over lapses in its anti money laundering controls.

"HSBC is strongly committed to fighting financial crime," the bank said in a statement.

"The bank has systems and processes in place to identify suspicious activity and report it to the appropriate government authorities. This case highlights the need for greater information sharing between the public and private sectors, each of whom holds important information the other does not."

RBS (>> Royal Bank of Scotland Group plc), which owns Coutts, and Standard Chartered (>> Standard Chartered PLC) also said they were committed to combating financial crime and money laundering. Standard Chartered said it would investigate any indications of suspicious activity.

The NCA said potential money laundering investigations were complicated when it was impossible to establish a criminal source for funds, such as drug supply, human trafficking or corruption without cooperation from the foreign jurisdictions.

(Additional reporting by Kylie MacLellan; Editing by Alexander Smith, Greg Mahlich)

By William James, Kirstin Ridley and Lawrence White