If an adult tries to message a teen who doesn't follow him, he will receive a notification that DM isn't an option. Teen users will also be shown safety prompts when messaging 'suspicious' adults.

"We have banned adults from direct messaging teenagers who don't follow them and introduce 'safety prompts' that will be shown to teens when they DM adults who have been 'exhibiting potentially suspicious behaviour'," Instagram said in a statement.

The company said that suspicious behaviour could include sending "a large amount of friend or message requests to people under 18."

Safety prompts will give teenage users the option to report or block adults who are messaging them.

The prompts will remind young users not to feel pressured to respond to messages and to "be careful sharing photos, videos, or information with someone you don't know".

Instagram said that this feature will be available in some countries this month, while it will be available globally "soon".

The photo-sharing app acknowledged that while many people are honest about their age, young people can lie about their date of birth.

"To address this challenge, we're developing new Artificial Intelligence and Machine Learning technology to help us keep teens safer and apply new age-appropriate features," the company noted.

Instagram also announced a new Parents' Guide with expert partners for more countries, including India.