A group of banking chiefs, insurance bosses and entrepreneurs are urging Prime Minister David Cameron to protect businesses from European Union bureaucracy and plans to tax financial institutions.
The 54 leaders, who together employ some 1 million people, argue in a letter to the Sunday Times that the changes "will continue to erode Britain's competitiveness in markets in which it has a unique global standing."
Cameron could face defeat next week on his effort to block former Luxembourg leader Jean-Claude Juncker from becoming European Commission president. Britain opposes the veteran advocate of EU integration and is pushing for a vote should the council put Juncker forward.
Cameron is anxious to show euro-sceptics in Britain, where anti-EU sentiment is high, that he is fighting for the country's best interests.