Based on the results of recently concluded stress tests, U.S. regulators told Citigroup Inc and Bank of America Corp they may need to raise more capital, the Wall Street Journal said, citing people familiar with the situation.

The shortfall in capital amounts to billions of dollars at BofA, the paper said, citing people familiar with the bank.

Both banks plan to respond with detailed rebuttals, the people told the paper, adding BofA's appeal is expected by Tuesday.

(Reporting by Ajay Kamalakaran in Bangalore, Editing by Ian Geoghegan)