Detective superintendent Russell Day of the metropolitan police told an all-party panel of MPs that banks were failing to report incidents of computer-based fraud, the Guardian reports.
Mr Day expressed concerns that this failure to disclose information was due to a lack of confidence in police or worries about publicity.
"Financial institutions are not reporting [these attacks] to law enforcement [agencies], and there could be two reasons for that," the Guardian quotes Mr Day as saying.
"It could be one of consumer confidence, but I think that to be honest it is their lack of confidence in law enforcement to deal with it. And they are right. Because of the global nature of this, it doesn't fit in with our priorities."