A boom in “Lolita” sites on Instagram, Facebook and other platforms is allowing paedophiles to target teenage girls without fear of arrest, an investigation by The Sunday Telegraph has found.

The phenomenon, where hashtags are used to enable older men to connect with younger women in online communities, has steadily increased since 2016 in the UK to garner more than three million posts last week on Instagram alone.

Britain’s leading children’s charities say paedophiles are using them to “hide in plain sight,” and are demanding the tech giants either ban the communities by blocking the tags or introduce tough age verification to prevent children engaging with them.

After being told of The Telegraph investigation, Facebook, which owns Instagram, announced an immediate worldwide ban on the tags.

“We have blocked all associated #DDLG hashtags on Instagram, which means they will no longer be searchable, viewable or recommendable,” said a spokesman. “Keeping young people safe on our platforms is a top priority.”

The tags - which stand for “Daddy Dom Little Girl” and have numerous permutations - are ostensibly designed for adult men interested in “submissive” role play relationships with women, which is entirely legal.

However, the US agency responsible for monitoring and reporting child sex abuse online says they are also being used as cover by predatory paedophiles to pursue children.