Consumer watchdogs have issued warnings over Bluetooth fidget spinners after versions of the popular toys with batteries in were found to burst into flames.

Two families, one in Michigan and another in Alabama, reported that the Bluetooth-enabled fidget spinners with inbuilt speakers caught fire.

In both cases, the gadgets were plugged in to charge and the battery inside overheated.

Kimberly Allums told American news station WBRC she heard her son screaming when he noticed his fidget spinner, made in China, had burst into flames after it had been charging for around 45 minutes. She said her son quickly put it in the sink to extinguish it but that the damage could have been a lot worse if they had been out of the house.

A similar case was reported in Michigan after a woman used a baby monitor charger to power her fidget spinner.

Fidget spinners, the three-pronged pieces of plastic with a spinning disc in the middle, were designed for children with autism and ADHD but have become the latest craze, leading them to be banned from many schools.