WASHINGTON – The Federal Reserve is proposing that large foreign banks keep a bigger financial cushion against unexpected losses for their U.S. affiliates.

The Fed governors, including Fed Chairman Ben Bernanke, voted 7-0 at a public meeting Friday to propose the rules. They are aimed at preventing another financial crisis. The rules were mandated by the 2010 financial overhaul and would apply to those foreign banks with $50 billion in worldwide assets that operate in the United States.

That means their U.S. affiliates would be subjected to the same capital reserve requirements as U.S. banks. The U.S. operations would have to take the form of a bank holding company, putting them under the Fed’s oversight.

Bernanke said the proposal “keeps a level playing field between foreign and domestic firms” without inhibiting foreign banks from doing business in the U.S.

The rules wouldn’t take effect until July 2015. The Fed estimates that about 107 foreign banks would be affected.

Rules proposed previously for U.S. banks would require them to hold capital worth at least 6 percent of the value of their assets, in line with international standards being phased in.

The Fed’s proposal would apply to 23 foreign banks that have both worldwide assets and assets in the U.S. of at least $50 billion each. Banks in that category include British bank HSBC, Germany’s Deutsche Bank, Canada’s TD Bank and Dutch bank ING.

A less stringent level would apply to 84 foreign banks with $50 billion or more in worldwide assets but less than $50 billion in U.S. assets.

Fed Vice Chairwoman Janet Yellen asked agency staffers at the meeting whether there’s a risk that many other countries could respond by imposing similar rules on U.S. banks operating abroad.