RBS Chief Executive Stephen Hester was criticizing a suggestion by Bank of England policymaker Robert Jenkins that banks could beef up capital by reducing bonuses, cutting risk-taking, or raising debt and equity.
"Some of the points being made were surprising," Hester told Parliament's Treasury Select Committee on Wednesday.
"One suggestion was that we go out and raise more capital. I would be interested to see the investor who wants to put more capital toward UK banks at the moment. They are thinking it is a dumb place to put more capital," he said.
HSBC Chairman Douglas Flint also criticized a proposal by Britain's Independent Commission on Banking (ICB) to make banks hold more loss-absorbing capital via "bail-in" bonds.
Flint said costs associated with such regulations were "too high to ignore", especially in terms of considering whether or not to keep HSBC's headquarters in London.
He said it would be some time before HSBC made a final decision over whether to move its headquarters, adding there were many reasons for HSBC to keep its base in London.
Earlier this month, HSBC said new banking regulations could cost it $2.5 billion a year, possibly making it too expensive to keep its headquarters in London.
Hester also told the committee the ICB may have underestimated the cost to the bank sector of its reforms, which entail ring-fencing retail banks from investment banking activities and making banks hold more capital.
The attempts by Britain's top banks to lobby against tough new rules have been criticized by politicians and regulators.
The Bank of England's Jenkins said this week the lobbying battles were short-sighted and intellectually dishonest.
"Bank lobbies are winning the battles and losing the war. As for bank leaders, they need to lobby less and lead a lot more," Jenkins said in a speech.
