British soldiers are facing disciplinary action after footage of them using an illegal torture device appeared on the internet.

The two squaddies, claiming to be from the Royal Engineers, filmed themselves using an electro-shock baton to stun each other while off-duty on a military base in Iraq.

Now human rights groups have demanded that military chiefs explain how the baton - known as 'the torturer's tool of choice' - fell into the hands of the soldiers.

Scroll to bottom to see the video...

Prepare for a shock: One of the soldiers braces himself as the other activates the electro-shock baton

Last night red-faced defence chiefs launched an inquiry into the source of the video and how the pair obtained the device.

The footage - entitled 'Taser fun!' - was posted on video-sharing website YouTube last month and involves two young squaddies who speak with Liverpulian accents.

The one-and-a-half minute clip shows the soldiers joking around with the device, beginning with the first soldier announcing 'This is me and Luke in the room - and we're gonna taser each other.'

The pair then proceed to administer painful electric shocks to each other as part of the prank.

The two squaddies laugh as they brandish the notorious device

After being shocked with the device, one of the soldiers says: 'Don't get done with a taser - it f****** hurts.'

Military bosses last night said that the pair, who have not yet been identified, will face disciplinary action and that the chain of command in Iraq had been informed of their antics.

After analysing the clip, arms experts from Amnesty International confirmed that the device was an electro-shock baton.

The organisation is now demanding to know how British troops gained access to the batons, which have been documented for their use in torture in countries such as Lebanon and China.

Amnesty International UK's Oliver Sprague said: 'What Amnesty wants to know is why are British soldiers brandishing an electro-shock baton?

'Look at that: it's a torch, but really ... it's a taser'

'These devices are illegal to own or sell in the UK because they are so widely used in torture all over the world.

'Electro-shock batons inflict severe pain at the touch of a button and leave no marks, earning them the title "the torturer's tool of choice".

'We'd certainly want to know how they got hold of it.

'We're not saying that these soldiers have used this to inflict pain on anyone except each other. But it's seriously worrying if British soldiers are able to obtain these devices so easily and film themselves mucking about with torture equipment.'

One of the pair is zapped, shouting: 'Don't get done with a taser - it f****** hurts'

Military insiders say that the baton may have been sent to the soldiers after they arrived in Iraq.

One Edinburgh-based soldier, who asked not to be named, said: 'When you go out on a tour you go through the same checks at the airport as civilians, so there'd be no way they could have taken that with them.

'One way it could have turned up is through the post, as the checks on letters and parcels are minimal.

'Why they'd want or need that while they're out there is anyone's guess, and it's even more of a puzzle as to why they'd film themselves with it.'

Tit for tat: The other soldier gets his turn at the receiving end of the baton

A spokesman for the Ministry of Defence last night confirmed that the pair are likely to face disciplinary action.

He said: 'We can confirm that the chain of command and the Royal Military Police have been alerted to the existence of this incident and are investigating. The device they are using is not military issue, and such items are not permitted in theatre.

'Service personnel are given direction as to what items are prohibited on operations, and the device in question would fall into that category. Individuals found in possession of such items will be subject to disciplinary or administrative action as appropriate.'

The video was posted on August 13 by a YouTube user calling himself 'lsccommodore' who is listed as being 49 years old and based in Britain.

In his introductory comments he writes: 'Off-duty squaddies will always find something mad to amuse themselves' - and adds a tag mentioning the Royal Engineers.

The export of electro-shock batons from the UK has been banned since 1997.

They can carry between 10,000 and 250,000 volts and have the potential to cause death through loss of coordination of heart muscle contraction.

Amnesty International claims that the devices have been documented in alleged torture cases in countries such as China, Saudi Arabia and Lebanon.