American Express has confirmed that its website has been hit by a distributed denial of service (DDOS) attack, which took it offline for 2 hours on Thursday, reported the New York Times (NYT) and other media outlets.
American Express Customers who tried to access their online accounts within the 2 hours were greeted by blank screens or an "an ominous ancient type face", NYT reported.
According to Bankinfosecurity.com, hacktivist group Izz ad-Din al-Qassam Cyber Fighters have claimed responsibility for the attack, although an Amex spokesperson has not confirmed this.
The group also claims credit for an unconfirmed attack against Bank of America, in updates on Twitter and a blog posted March 28.
Online site The Daily Dot added that in addition to the website, Amex apps were also affected.
In a statement, the company acknowledged the attack and added: ""We experienced intermittent slowing on our website that would have disrupted customers' ability to access their account information.
"We had a plan in place to defend against a potential attack and have taken steps to minimize ongoing customer impact."