A teenager was killed by an electric shock while charging his smartphone in bed.

Petchkao Yimyam, 15, had plugged the device into a power extension before going to sleep in his room in Nonthaburi, Thailand.

As he shifted on the mattress on the floor, he is believed to have rolled over the broken charging cable and was zapped to death by the powerful electric current.

Police were notified when Petchkao's brother Nattapon Amornwong discovered the dead body on March 30.

Initial investigations found dark burn wounds on the lad's right arm, as well as burn marks along the length of the charging cable.

An officer from the Rattanathibet Police Station said: 'The scene was a two-storey townhouse where a young man was found shirtless and dead on a mattress.

'There were black marks on his body and the phone charger next to him. We believe he suffered an electric shock, and had been dead for at least eight hours before he was found.'

Nattapon said he entered their room at around 8 am and found his brother still on the mattress.

Thinking his brother had stayed up late as usual, he grabbed his phone and left - only to return at around 5 pm to see Petchkao still lying in the same position.

Nattapon said: 'He had a habit of sleeping in, so I thought nothing of it when I saw him still in bed in the morning. But later that afternoon, I came back and he was still lying there. When I took a closer look, I saw that his skin was darkening and he was already stiff. I rushed to call our mum for help.'

The post-mortem examination found that Petchkao had died of an 'electric shock causing the heart to beat irregularly'.

Petchkao's aunt, Jean, said the lad was healthy and did not have any underlying conditions. His funeral was being held at the Wat Chomphu Wek temple in Nonthaburi.