NEW YORK — US units of foreign lenders may be required to comply with tougher capital rules that some banks sought to skirt, three people with knowledge of the discussions said.

The Federal Reserve, drafting standards for the nation’s largest banks, may force non-US firms to house all of their businesses within a US holding company, said the people, who requested anonymity because the rules have not been finalized. That means local units would have to meet minimum capital standards, regardless of their parents’ resources.