Bank of America acknowledged yesterday that its lax operations allowed South American money launderers to illegally move $3 billion through a single Midtown Manhattan branch, closing the latest illicit-finance investigation brought by Robert M. Morgenthau, the Manhattan district attorney.

Mr. Morgenthau said he hoped the settlement would encourage the federal government to do more to track illicit money transfers, including terrorist financing.

No indictment was sought “because we don’t want to put banks out of business,” Mr. Morgenthau said.

Bank of America, in a statement, said that it “takes seriously its anti-money laundering obligations” and that it “never knowingly does business with persons, organizations or businesses engaged in illegal activities and did not in this case.”

Most of the funds came from Brazil via a licensed money transmitter in Uruguay and then to the Bank of America branch, which allowed funds to reach unlicensed money transfer firms in the area, Mr. Morgenthau said. He noted that the area where Brazil borders Uruguay has been identified by federal authorities as a hot spot of suspected terrorist financing.