Shadow chancellor George Osborne has told the BBC that if the Conservatives win the general election they will copy US plans to limit the size of banks.
Under the proposals outlined by President Barack Obama, US retail banks will face curbs on their riskier activities.
This could lead to the largest US banks being broken up.
The Treasury said it would consider President Obama's comments on bank reform "very carefully".
'Welcome move'
BBC business editor Robert Peston said Mr Osborne's comments would "generate profound fear in the boardrooms of Barclays and Royal Bank of Scotland".
Shares in both banks fell sharply on Tuesday, with Royal Bank of Scotland losing 7% - the biggest decline on the UK's main FTSE 100 share index. Barclays lost 5.9%.
Under President Obama's proposals, retail banks would be banned from using their own money in risky financial transactions.
This would prevent them from investing in hedge and private equity funds, or engaging in so-called proprietary trading.
"This is a welcome move by President Obama that accords very much with our thinking," said Mr Osborne.
"I have said consistently that we should look at separating retail banking from activities like large scale propriety trading - and that this was best done internationally."
Shadow chancellor George Osborne has told the BBC that if the Conservatives win the general election they will copy US plans to limit the size of banks.Under the proposals outlined by President Barack Obama, US retail banks will face curbs on their r
Following Lloyds annoncement today about returning to profit in 2010 , I feel RBS is going to follow suit.. I think it is still worth a speculative buy...I am going to think about buying some more shares.
Following Lloyds annoncement today about returning to profit in 2010 , I feel RBS is going to follow suit.. I think it is still worth a speculative buy...I am going to think about buying some more shares.