While the leaders managed to paper over any rifts by the time they emerged from their meeting, their lack of agreement on a British-style guarantee of loans made between banks worried economists.

If other countries do not follow the same course as Britain, they said, it could destabilize the financial system, because money may flow to Britain from countries without those same guarantees.

“You now have the full faith and credit of the British government standing behind the banking system,” said Barry Eichengreen, a professor of economics at the University of California, Berkeley. “The British could suck deposits from continental Europe and even the United States.”