British bank HSBC apparently did not see the humor in an Instagram video that shows six of its employees staging an ISIS-style "mock beheading," USA Today reported.

The institution called the footage "abhorrent," and all workers involved in the incident have been let go, the newspaper noted.

The video was shot during team-building exercise and then posted on the Internet, the British tabloid the Sun detailed. It shows the workers dressed in jumpsuits and ski masks similar to those worn in propaganda material released by ISIS, a terrorist group that refers to itself as the "Islamic State" and controls large swaths of territory across Iraq and Syria.

The organization has been known for the brutal rule it has established in areas under its rule; it has also frequently grabbed international headlines with its executions of opponents, of those who refuse to adhere to its extreme interpretation of Islam, as well as of foreign journalists and aid workers.

London-based HSBC, the world's third largest bank by assets, issued a public apology and said it did not "tolerate inappropriate behavior."

"As soon as The Sun brought this video to our attention, we took the decision to (fire) the individuals involved," the bank said in a statement. "This is an abhorrent video, and HSBC would like to apologize for any offense caused," it added.

The video had caused a particular uproar in the United Kingdom because Alan Henning and David Haines, two British aid workers murdered by ISIS, had both been wearing similar orange jumpsuits when they were beheaded in Syria, the Sun noted.

Henning, a 47-year-old volunteer, was captured by the terror group in 2013 when he was delivering goods for civilians affected by the Syrian civil war between ISIS, rebels and forces loyal to dictator Bashar al-Assad. His killing was documented in a video the organization released in October 2014.

Henning's death came a month after ISIS had apparently beheaded Haines, a 44-year-old aid worker, who had also been abducted in 2013.