Meta Platforms' Facebook and Instagram have been charged with breaching landmark EU tech rules and must do more to block children under 13 from accessing the social networks, EU regulators say.

The charges or so-called preliminary findings under the Digital Services Act, which requires Big Tech to do more to tackle illegal and harmful content on their platforms, came after a two-year investigation by the European Commission.

Meta, which said it disagreed with the preliminary findings, can respond to the charges and take measures before the commission issues a final decision.

DSA breaches can cost companies fines as much as six per cent of their global annual turnover.

The EU move comes amid growing concerns worldwide about the impact of social media on children, businesses and governments, prompting calls on Big Tech to be more proactive and take more effective measures.

The EU tech enforcer said Meta did not do enough to enforce its restrictions on children under 13 from using Facebook and Instagram, and measures to identify and remove them when they did access the services were inadequate.

It said 10 per cent to 12 per cent of children under 13 in Europe used Facebook and Instagram.

"Our preliminary findings show that Instagram and Facebook are doing very little to prevent children below this age from accessing their services," EU tech chief Henna Virkkunen said in a statement.

"Terms and conditions should not be mere written statements, but rather the basis for concrete action to protect users - including children."

Meta says it has measures in place to detect and remove accounts from children under 13 and that it will announce additional measures.

"Understanding age is an industry-wide challenge, which requires an industry-wide solution, and we will continue to engage constructively with the European Commission on this important issue," a Meta spokesperson said.

The commission said both platforms must change their risk assessment methodology and they need to strengthen measures to prevent, detect and remove minors from their services.

If regulators feel they still do not do enough to satisfy them, they can still impose a fine, although this step would be many months away.