A power bank exploded inside an underground train station in China, causing panic on a metro platform.

The portable charging device was inside a passenger's jacket pocket as he walked along the platform at Shanghai West Railway Station on Shanghai Metro Line 15 on January 5.

Suddenly, the traveller was startled by a blast and sparks coming from his pocket.

Dramatic footage shows the panicked commuter rushing down an escalator with flames on his clothing.

One onlooker said: 'We were stunned to see the man running away with flames on his jacket. People started screaming, and we immediately alerted station staff.

'Everyone moved back while he ran towards the escalator. Thankfully, he was safe, and the fire was put out quickly.'

Preliminary findings suggest the power bank was purchased last month and carried China's mandatory 3C safety certification.

Officials said the device was not in use at the time of the explosion.

Fire authorities later warned that power banks can still ignite even when not in use. They said fires may be caused by internal short circuits, manufacturing defects in battery cells or protection circuits, accumulated wear, high ambient temperatures, or damage linked to previous improper charging.

No serious injuries were reported.