A warning has been issued over potentially deadly mobile phone 'stun guns' which are being brought back to the UK by holidaymakers.

A video demonstrating one of the devices, which looks exactly like an iPhone , was posted on social media by the National Crime Agency today.

The 'phone' can be seen firing an electric shock from the top as a button is pressed on the side.

Alongside the short clip, the organisation said: "Brought one of these back from holiday? Be aware they are # IllegalWeapons in the UK."

The devices, known as "Electronic Riot", are capable of delivering a potentially deadly 80,000 volt shock and are readily available online for as little as 15.

They are illegal in the UK and possession of one can carry a jail sentence, but stun guns can be bought in the US, where they are marketed as a personal safety device.

The fake phone has electrodes at the top, with the electric charge triggered by the mobile phone's "volume" buttons.

The stun guns are understood to be shipped from Hong Kong to Switzerland before being delivered to the UK.

Instructions inside the box say the iPhone stun gun is an "ideal present for friends and family".

The packaging bears a signed declaration on the box reading: "This item does not contain any dangerous article or articles prohibited by legislation or by postal or customs legislation."

Tourists are bringing potentially deadly mobile phone STUN GUNS back to the UK - Mirror Online