British bank HSBC fired six staff after they filmed a mock Islamic State-style execution video during a team-building day out and posted footage online, a spokesman confirmed on Tuesday.

The bank described the video, showing staff members in balaclavas holding a fake knife over a kneeling man in an orange jumpsuit, as "abhorrent".

"We took the decision to sack the individuals involved," a spokesman for the bank said.

"This is an abhorrent video and HSBC would like to apologise for any offence caused."

The employees filmed the video on an HSBC team-building day at a go-karting centre in Birmingham and posted it on Instagram before deleting it, according to newspaper The Sun, which published the video on its website.

In the eight-second clip, a kneeling man in a jumpsuit is held by the shoulders while a colleague wields a coat hanger like a knife above him, as though preparing to cut off his head.

One staff member shouts "Allahu Akbar" (God is greater in Arabic) during the clip.

The staging recalls gruesome beheading videos released by the IS group, which has executed over 3,000 people in Syria in the year since it declared an Islamic "caliphate" in Syria and Iraq, according to the Syrian Observatory for Human Rights.

IS killed a series of international hostages dressed in orange jumpsuits, including British aid workers David Haines and Alan Henning, in videos that caused shock when they were released last year.

HSBC has recently weathered a string of bad publicity, including allegations its Swiss private banking arm helped wealthy clients dodge tax, and fines by regulators for attempting to rig foreign exchange markets.

In June it announced it would cut its global workforce by up to 50,000 as it exits Brazil and Turkey and mulls relocating its headquarters back to Asia from London.