NEW YORK • A wave of hefty fines against major banks in the past decade spurred an explosion in the number of transactions that lenders flag as suspect to the US government. It's not clear all the scrutiny is making a difference.

Banks moved money for people or entities they could not identify, and in many cases failed to file the required suspicious activity reports until years later, according to an investigation released over the weekend by the International Consortium of Investigative Journalists (ICIJ). The report, based on leaked documents obtained by BuzzFeed News and shared with the consortium, said that in some cases the banks kept moving illicit funds after receiving warnings from US officials.