Two banks targeted by hacktivists are seeing their websites swamped.

Both U.S. Bank (USB) and PNC Bank (PNC) said Thursday their websites have been hit by a torrent of requests that could delay access for some customers.

The institutions are among five banks targeted Monday by the al Qassam Cyber Fighters Group, which claimed responsibility for a so-called denial of service attack on both U.S. Bank and PNC in September amid a series of attacks on at least 10 financial institutions worldwide.

U.S. Bank spokesman Tom Joyce told American Banker the bank saw "unusual and coordinated high traffic volume" at its website starting at roughly 11:00 a.m. Eastern time on Wednesday and again about 24 hours later. "It lasted most of the day and started again [Thursday] morning," Joyce said. "Our website has performed very well; however, customers could experience intermittent delays."

PNC took to Facebook Thursday morning to tell customers the bank was experiencing "an unusual volume of Internet traffic consistent with recent threats against U.S. banks" and that access to its online and mobile banking had slowed.

The digital assault on PNC recurred two days after the bank said it had experienced a crush of Internet traffic and warned customers who use the bank's online and mobile services to expect possible delays.

"At this time, all systems are operating normally," PNC spokesman Fred Solomon later said in an email.

Joyce says U.S. Bank is working to maintain clear connections to the Internet and urging customers who encounter snags with online or mobile banking to call the bank via its toll-free number or stop by one of its branches or ATMs. He also says U.S. Bank has been in contact with "federal law enforcement."

The al-Qassam group, which also has threatened JPMorgan Chase (JPM), Bank of America (BAC) and SunTrust (STI) with more attacks, pledges to keep up the assaults, which flood lines that connect banks to the Internet, as long as a trailer for "The Innocence of Muslims," American-made, anti-Muslim film, remains posted on YouTube.