NEW YORK (Bloomberg) - JPMorgan Chase & Co. CEO Jamie Dimon, whose bank had promised to build a European headquarters in London, told UK Chancellor of the Exchequer Alistair Darling a 50 percent tax on bonuses would unfairly penalise the US lender, a person close to the firm said.

Dimon told Darling that JPMorgan never took a UK bailout and said plans to build a European headquarters at Canary Wharf show the New York-based company's commitment to London, the person said. JPMorgan, the second-largest US lender by assets, may scrap the Canary Wharf project because of the bonus tax, the Financial Times reported, citing an unidentified bank executive.

Financial firms may face higher costs after Darling said on December 9 he would impose a 50 percent tax on discretionary bonuses greater than 25,000 pounds ($40,000). European and US regulators imposed pay curbs after the world's banks ran up $1.7 trillion in losses and writedowns during the global financial crisis.

"Jamie is quite a controlled character, so this is an example of the fury that has been created," said Stuart Fraser, the head of policy for the City of London, the financial district's lobby. "There is a real sense of indignation and anger about this tax."

The tax may apply to compensation for about 20,000 people with the cost imposed on employers. During the call, Dimon, 53, mentioned that JPMorgan has paid UK taxes and reminded Darling of plans to spend about $2.4 billion on the Canary Wharf project, according to the person, who declined to be identified because the discussions were private.

The conversation with Darling was reported earlier by the London Telegraph. JPMorgan spokesman David Wells declined to comment. A UK Treasury spokesman yesterday defended the tax as fair because it would apply to all banks and said he could not confirm the telephone conversation.

Financial firms are threatening to leave the UK because they say increased taxes and regulation make London less attractive. Tullett Prebon plc., the inter-dealer broker, said it will help employees relocate.

BlueCrest Capital Management Ltd., a London-based hedge fund firm that oversees about $15.4 billion, plans to open a Geneva office, a person familiar with the situation said last month. As many as 50 of BlueCrest's 300 employees in London may move, the person said.

Deutsche Bank AG CEO Josef Ackermann said on December 12 that Germany has a "comparative advantage" over other financial hubs because it doesn't plan to tax bonuses. The bank said it plans to spread the costs of the UK bonus tax to all employees worldwide.

The new levy forced Dimon to consider, "Do we want to be in a more tax-friendly, corporate-friendly environment?" said Jeff Harte, an analyst in Chicago for New York-based Sandler O'Neill & Partners LP. "There are opportunities all over Europe. There are a lot of cities that could handle operation hubs."

The U.K. Treasury is working with banks to identify employees who are excluded from the tax, and Darling said on December 16 he will resist calls to change the policy. Banks cannot avoid the levy by arguing that some activities are not defined as banking, he said.

Shares of Songbird Estates plc., which controlled more than half the buildings in the Canary Wharf estate, were little changed at 157 pence at 3.04 p.m. in London trading. JPMorgan's stock dropped 19 cents to $41.53 at 10:02 a.m. in New York Stock Exchange composite trading. A spokesman for Songbird declined to comment.