The 54 leaders, who said they together employ some 1 million people, argued in a letter to the Sunday Times that red tape and plans in the EU to tax financial institutions "will continue to erode Britain's competitiveness in markets in which it has a unique global standing."
The letter comes amid a heated debate in Britain about its place in the 28-nation EU. The main political parties have been rattled by the rise of the euroskeptic U.K. Independence Party, which advocates pulling Britain out of the EU and stopping the unfettered right of EU citizens to enter Britain.
Anxious to take a stand, Cameron has actively sought to block former Luxembourg leader Jean-Claude Juncker from becoming the president of the European Commission - the EU's executive arm. Britain opposes the veteran advocate of EU integration and is pushing for a vote should the council put Juncker forward.
Juncker is the candidate of conservatives who finished first in European Parliament elections, but Cameron has also cast him as epitomizing many of his objections with EU policies. German Chancellor Angela Merkel has said she might consider concessions to Britain if they don't get their way on the presidency issue.
"We can't fulfill every wish, but that means that in other areas we can think about what is very important to Great Britain," she said last week after meeting with her Danish counterpart.