The Wells Fargo (WFC) website became the latest victim of cyber attack when it experienced intermittent outages Tuesday. After eliciting hundreds of complaints, the website resumed operations to provide regular services to customers.

The Wells Fargo website attack follows attacks against Bank of America (BAC) and J.P. Morgan Chase (JPM).

About 220 customers of the fourth largest bank by assets filed complaints with, the Wall Street Journal reported.

The report follows financial services industry group warning the U.S. banks, brokerages and insurers to be on high alert for cyber attacks after Bank of America Corp and JP Morgan Chase experienced outages on their websites.

Wells Fargo's problems cropped up the same day an unidentified person called on "cyberspace workers" to attack the bank's site. Apparently, a posting on also warned of attacks against U.S. Bancorp and PNC Financial Services Group Inc, Reuters has reported.

The posting stated that the attacks would continue till a video insulting the Islamic prophet Muhammad was removed from the Internet, the Los Angeles Times reported, adding, computer security expert Dmitri Alperovich investigating the attacks stated it could not be determined what the actual motivation was.

Alperovitch, co-founder of the security firm CrowdStrike Inc, told the Los Angeles Times that the posting "appears to be accurate in terms of predicting future attacks, but I wouldn't necessarily take at face value any of its claims about attribution or the video."

Commenting on the threats, a U.S. Bancorp spokesman told Reuters that the bank was aware of the posting and was working closely with law enforcement authorities. A PNC spokesperson was yet to comment on the issue.

Senator Joseph Lieberman, chairman of the Senate's Homeland Security and Governmental Affairs Committee, told Reuters Friday that he believed Iran was behind the attacks.

Reportedly, the attacks that commenced in late 2011 and escalated this year were identified primarily as "denial of service" campaigns, as they disrupted banks' websites and corporate networks with overwhelming incoming web traffic.