Britain's largest bank has fired six of its employees for taking part in a video showing a mock Islamic State-style execution.

The seven-second clip shows HSBC staff members in balaclavas standing over an Asian colleague dressed in an orange jumpsuit, whose hands are tied behind his back. A coat hanger is used by one the men as a pretend knife.

One of them then shouts "Allahu Akbar" — Arabic for "god is greater" – a phrase used by Islamic State militants during executions.

The stunt was filmed while the employees were on a corporate team-building exercise and was posted on Instagram but quickly deleted, reports The Sun.

It is believed that the men were part of a Birmingham-based legal team. One source told the newspaper: "It's shocking they would think this is funny."

An HSBC spokesperson said such behaviour would not be tolerated. "As soon as The Sun brought this video to our attention we took the decision to sack the individuals involved," they said. "This is an abhorrent video and HSBC would like to apologise for any offence caused."

The video is reminiscent of gruesome Islamic State beheadings that shocked the world, including the murder of British aid workers David Haines and Alan Henning.

IS militants have executed over 3,000 people in Syria in the year since it declared an Islamic "caliphate" in Syria and Iraq, the Syrian Observatory for Human Rights told The Guardian.

HSBC has suffered months of bad publicity, including claims that it had helped its wealthiest clients avoid paying tax and large fines for trying to rig foreign exchange markets.