Major international banks have denied claims they are helping clients avoid tax by using complex offshore structures. 

HSBC, Credit Suisse and the Royal Bank of Scotland-owned bank Coutts Trustees have been named in a list of lenders who have helped to set up structures which can make it hard for tax officials to pinpoint the flow of money.

This is according to the International Consortium of Investigative Journalists (ICIJ). 

Its findings are based on more than 11 million documents from the Panama-based law firm Mossack Fonseca, which have exposed a series of schemes used by wealthy individuals. 

The Panama Papers leak has revealed that more than 500 banks, including their subsidiaries and branches, registered nearly 15,600 shell companies with Mossack Fonseca, according to the ICIJ.

UK banking giant HSBC said it was working closely with authorities to combat financial crime and has put sanctions in place.

"Our policy is clear that offshore accounts can only remain open either where clients have been thoroughly vetted (including due diligence, 'Know Your Customer', source of wealth, and tax transparency checks), where authorities ask us to maintain an account for the purposes of monitoring activity, or where an account has been frozen based on sanctions obligations," a spokesman said. 

Credit Suisse chief executive Tidjane Thiam said: "We do not condone structures for tax avoidance".

"Whenever there is a structure with a third party beneficiary we insist to know the identity of that beneficiary. We as a company, as a bank only encourage the use of structures when there is a legitimate economic purpose," he added.

Meanwhile, a spokesman for Coutts Trustees said the bank was committed to the highest standards when  complying with regulation. 

WWe require all clients to be tax compliant as a condition of receiving our products and services and take a risk-based approach to identify and prevent tax evasion that relies upon extensive anti-money laundering systems and controls, including the requirement to understand the source of clients' wealth," the spokesman said. 

"The provision of trust and administration services is an entirely legitimate and key aspect of wealth management and succession planning," he added.