BRUSSELS, May 16 (Reuters) - Meta Platforms' ( META )

social media sites Facebook and Instagram will be investigated

for potential breaches of EU online content rules relating to

child safety, EU regulators said on Thursday, a move that could

lead to hefty fines.

Tech companies are required to do more to tackle illegal and

harmful content on their platforms under the European Union's

landmark Digital Services Act (DSA), which kicked in last year.

The European Commission said it had decided to open an

in-depth investigation into Facebook and Instagram due to

concerns they had not adequately addressed risks to children.

Meta submitted a risk assessment report in September.

"The Commission is concerned that the systems of both

Facebook and Instagram, including their algorithms, may

stimulate behavioural addictions in children, as well as create

so-called 'rabbit-hole effects'," the EU executive said in a

statement.

"In addition, the Commission is also concerned about

age-assurance and verification methods put in place by Meta."

The regulator's concerns relate to children accessing

inappropriate content.

Meta is already in the EU's crosshairs over election

disinformation, a key concern ahead of crucial European

Parliament elections next month. DSA violations can lead to

fines of as much as 6% of a company's annual global turnover.