By Mrinmay Dey and Angela Christy M

(Reuters) -Britain's privacy watchdog, the Information Commissioner's Office, on Monday launched an investigation into how TikTok, Reddit and online image sharing website Imgur safeguard children's privacy.

Social media companies use complex algorithms to prioritise content and keep users engaged. However, the fact that they amplify similar content can lead to children being influenced by increasing amounts of harmful material.

The watchdog said it is probing how Chinese company ByteDance's short-form video-sharing platform TikTok uses 13–17-year-olds' personal information to suggest content in their feed.

TikTok's recommender systems operate under comprehensive measures that protect privacy and safety of teens, including restrictions on content allowed in their feeds, a TikTok spokesperson told Reuters in an emailed statement.

Social media and discussion platform Reddit, and Imgur, face UK investigation over their handling of children's personal data and age verification practices, the data watchdog said.

"If we find there is sufficient evidence that any of these companies have broken the law, we will put this to them and obtain their representations before reaching a final conclusion," the Information Commissioner's Office said in a statement.

In 2023, the ICO fined TikTok 12.7 million pounds ($16 million) for breaching data protection law by using the personal data of children aged under 13 without parental consent.

Reddit has been working closely with the ICO and intends to comply with all relevant regulations in the countries in which it operates, a spokesperson from the company told Reuters in an email.

"Most of our users are adults, but we have plans to roll out changes this year that address updates to UK regulations around age assurance," the Reddit spokesperson said.

Imgur did not respond to a Reuters request for comment.

Britain has passed legislation that set tougher rules for social media platforms, including a mandate for them to prevent children from accessing harmful and age-inappropriate content by enforcing age limits and age-checking measures.

Social media platforms including Facebook, Instagram and TikTok are required to "tame" their algorithms to filter out or downgrade harmful material to help protect children under proposed British measures published last year.

($1 = 0.7933 pounds)

(Reporting by Angela Christy and Mrinmay Dey in Bengaluru; Editing by Lincoln Feast and Gerry Doyle)