A hot water bag exploded on a boyfriend's arm as his partner pressed it to soothe his muscles.

CCTV footage shows Waranya Lobpuen, 31, pressing the warm bag onto her partner Thuchchai Samutsen's arm before he jumped away as he felt the hot water dripping onto his skin.

He suffered burns on his arm and belly, which became swollen, and reached out to the store manager regarding the alleged defective item from a shop in Rayong, Thailand.

Thuchchai said: ‘The store should take better care of customers rather than making them repeatedly approach for assistance.'

Meanwhile, girlfriend Waranya said she bought the hot water bag with a cute pink design and filled it with water that was not too hot.

She said: ‘I even tested it first to ensure it wasn't too hot. What if children bought it and the same thing happened?'

She added they treated his wounds with aloe vera jelly every day following the incident on July 1.

She said: ‘We contacted the convenience store but they did not seem to care. We reached out for help and aways told us that it was under process.'

Waranya added there were no investigations yet to check if the water scalded her boyfriend.

She said: ‘I don't know what they put in there, but it burned the skin. I hope someone could offer an explanation because it's dangerous to sell them like that.'