Upon taking power in January, president-elect Barack Obama plans to clamp down on international tax havens, including Jersey, Guernsey and the Isle of Man in a stand-off with Gordon Brown. Advisers to Obama have estimated the move could raise at least $50bn (£32bn) per year in lost US tax revenues, and Washington sources have said leading accountancy firms have already hired lobbyists in anticipation of a battle to scale down the measures, The Guardian reports. International pressure to ban tax havens in order to restore the global financial system has increased, with a conference being held in Washington next week by the leaders of the world's 20 most powerful economies to plan reforms. Obama's key aides have said he will introduce a similar law to the Stop Tax Haven Abuse Act put to Congress last year, of which Obama was a signatory, which blacklisted Jersey, Guernsey and 32 other jurisdictions. Key measures by Obama are likely to encompass revealing the owners of secretive trusts, prohibiting accountants from charging fees on specific tax services, and identifying 'offshore secrecy jurisdictions' that 'unreasonably restrict US tax authorities from obtaining needed information'.