A group of hacktivists who claimed responsibility for a series of cyberattacks on some of the nation's biggest banks is vowing to resume its offensive.

The al-Qassam Cyber Fighters said Tuesday it has revived its operation because a trailer for an anti-Muslim film called "The Innocence of Muslims" remains on YouTube despite demands from the group that the clip be removed.

In January, the Cyber Fighters halted their campaign, which has included a series of electronic assaults that have bogged down websites and maddened customers of at least a dozen banks since September, after someone took down one version of the trailer. The group warned it would resume the attacks unless roughly a dozen versions of the video that remained on the website came down as well.

In an email Tuesday, the Cyber Fighters identified themselves as "Muslim youth" and pledged to direct so-called denial of service attacks against American banks this week "during working hours." The group added it would stop its campaign "only when the insulting movies are removed from the Internet."

For its part, YouTube has said the trailer comports with the company's content guidelines. That means the clip will stay on the service until whoever posted the video decides to remove it, although YouTube warns viewers the content may be "potentially offensive or inappropriate." Several versions of the trailer remained on YouTube on Tuesday.