Amazon has "fixed" its Alexa voice assistant after it told a 10-year-old girl to touch a penny to the prongs of a plugged-in phone charger.

Kristin Livdahl, the girl's mother, said it happened when the US family asked the Echo smart speaker for physical challenges to do because the weather was bad outside.

She tweeted a screenshot from the activity log which showed its response.

Citing a third-party website, it told her daughter: "The challenge is simple: plug in a phone charger about halfway into a wall outlet, then touch a penny to the exposed prongs."

The so-called "penny challenge" spread on sites such as TikTok last year, but firefighters warned it could cause a spark that may badly damage electrical systems and even start a fire.

Amazon said it quickly updated Alexa to stop it happening again.

A statement said: "Customer trust is at the centre of everything we do and Alexa is designed to provide accurate, relevant, and helpful information to customers.

"As soon as we became aware of this error, we took swift action to fix it."