Lloyds Banking Group Plc on Jan. 11 was hit by a distributed denial of service cyber attack, initially thought to be an IT glitch, which left some of the bank's customers unable to access their online accounts for two days, Reuters reported Jan. 23, citing a "source familiar with the incident."

The London-based lender is working with authorities to determine who may be behind the attack.

Such attacks, which involve overloading a server with huge volumes of traffic from multiple systems, could be part of plans to extract ransom or distract security teams to be able to break into an organization's network, Reuters reported.

No customers suffered any losses, with the bank reportedly saying that "only a small number of customers" experienced problems accessing their accounts.