Short-form video sharing app TikTok has been handed the largest ever fine for a US case involving children's data privacy.

The company has agreed to pay $5.7m (£4.3m) and implement new measures to handle users who say they are under 13.

The Federal Trade Commission (FTC) said the Musical.ly app, which was later acquired and incorporated into TikTok, knowingly hosted content published by underage users.

It has ordered TikTok to delete the data.

Additionally, as of Wednesday, TikTok users in the US will be required to verify their age when they open the app.

However, like many social networks, age verification is implemented on a trust basis - a person signing up simply has to lie about their date of birth in order to get around the check.

"We care deeply about the safety and privacy of our users," the firm said. "This is an ongoing commitment, and we are continuing to expand and evolve our protective measures in support of this."

Despite this, TikTok said it would not be asking existing users in other countries, including the UK, to verify their age as the settlement only applied to the US.

After being one of the most downloaded apps of 2018, TikTok has an estimated base of 1 billion users worldwide.