The biggest private bank in the United States is trying to wean itself off government assistance.

A customer uses a Bank of America ATM in Charlotte, North Carolina (File)Bank of America received more than $45 billion in emergency loans and other support from the U.S. government during the peak of the financial crisis and is offering to pay back almost half that.

Bank officials have been trying to convince government regulators the financial firm has raised enough money and is no longer in danger of failing. And on Monday, Bank of America offered to pay the government an additional $425 million to end a program that limited its losses during the takeover of troubled investment firm Merrill Lynch.

Still, not all U.S. officials are satisfied.

One regulatory body, the Securities and Exchange Commission, is suing Bank of America, accusing the private bank of failing to tell the public about $3.6 billion in bonuses paid to executives at Merrill Lynch before the takeover was completed.

Regulators had hoped to settle the Bank of America-Merrill Lynch case for $33 million, but that proposal was rejected by a U.S. judge.

Several other major U.S. banks, including JPMorgan Chase, Morgan Stanley, U.S. Bancorp and BB&T, have already returned billions of dollars in emergency aid. But some major investors remain wary about the long-term stability of some major U.S. banks.

Singapore's sovereign wealth fund, the Government of Singapore Investment Corporation, said Tuesday it reduced its holdings in Citigroup, which was once the world's largest bank, by almost half.

In doing so, the fund made a $1.6 billion profit.

Some information for this report was provided by AFP and Reuters.