JP Morgan boss Jamie Dimon told Congress on Tuesday that his bank was "not too big to fail" as he fended off calls for tighter regulation following its $2bn-plus trading loss.

At a sometimes heated hearing, congressman Sean Duffy asked Dimon whether the bank was too big to regulate, too big to manage and too big to fail – charges Dimon denied. "Why should we allow you to be so big that if you go under, we are going to have to bail out your creditors?" asked representative Brad Sherman.

This was Dimon's second appearance in as many weeks before a Washington panel. Last week a Senate committee quizzed the JP Morgan boss on the still mounting losses at the bank's London offices. The House committee was far more combative in tone.

Congressman Barney Frank, co-author of the Dodd-Frank regulations brought in after the last financial crisis, asked Dimon if his wages would be subject to "clawback" following the disclosure of the losses. Last week Dimon said staff at the bank who were responsible for the London losses could have their pay reclaimed under the bank's so-called clawback provisions. Dimon said that decision would be for the board to decide.

Dimon has been Wall Street's fiercest critic of elements of the Dodd-Frank rules. Frank said Dimon had said the bank had a "fortress balance sheet" that would protect it from losses like those in London. "What about institutions that are less impregnable, maybe a chain link fence, a picket fence or two?" asked Frank. Dimon said "all American banks are better capitalized" after the financial crisis. "Don't filibuster," said Frank.

Politicians on both sides of the House are currently working on legislation aimed at tackling fears that after the collapse of their rivals in the credit crisis some financial institutions have become so large that their collapse could cause enormous damage to the US economy.

Dimon was repeatedly asked about the too-big-to-fail concept. "We can not have too big to fail. We have to get rid of too big to fail so that a bank can fail without doing damage to the economy." he said.

But he defended JP Morgan's size. Dimon said a lot of banks were "the port in the storm" and the JP Morgan's size and diversification had allowed it to pull through the credit crisis and "allowed us to do the things you wanted to do" including buying failing banks like Washington Mutual, lending money to California and investing in Chrysler.

The bank boss also fended off questions about the likely impact of the London losses or how big they would grow. He said JP Morgan would remain profitable after the loss. Asked if the losses could grow to $50m he said: "Not unless the moon strikes the Earth."

Dimon and regulators were quizzed by the panel about the role of London and its regulation in the losses. "Every big trading disaster happens in London. I would like to know why," representative Carolyn Maloney asked regulators earlier in the day. "It is a pattern."

"Our problem has nothing to do with London or any loopholes," Dimon said. But he said if regulation was tightened up for US banks operating overseas, US banks would lose business. "We will lose a lot of business. They will not move to London, but I assure they will be in Singapore, in other parts of the world," he said.