Wells Fargo & Co on Tuesday became the latest bank to suffer problems with its website amid heightened concerns about cyber attacks against U.S. financial institutions, Reuters reported.

The fourth-largest U.S. bank by assets confirmed that some of its customers experienced intermittent access issues Tuesday.

A financial services industry group last week warned U.S. banks, brokerages and insurers to be on heightened alert for cyber attacks after Bank of America Corp. and JPMorgan Chase & Co. experienced unexplained outages on their public websites.

Reuters reported on Friday that Iranian hackers have repeatedly attacked Bank of America, JPMorgan and Citigroup Inc. over the past year as part of a broad cyber campaign targeting the United States since late 2011. The attacks disrupted the banks’ websites and corporate networks by overwhelming them with incoming web traffic.