Cyberflashing is to become a criminal offence, with perpetrators facing up to two years in jail under government plans to strengthen the upcoming online safety bill.

Three-quarters of girls aged 12-18 have been sent unsolicited nude images of boys or men, according to research published in 2020. A revised version of the online safety bill is expected to be published the week that will include a number of new offences in addition to cyberflashing.

The culture secretary, Nadine Dorries, said: “The forthcoming online safety bill will force tech companies to stop their platforms being used to commit vile acts of cyberflashing. We are bringing the full weight on individuals who perpetrate this awful behaviour.”

The move to criminalise cyberflashing in England and Wales follows recent action to criminalise upskirting, which is now a criminal offence, and a proposal this year to do the same for breastfeeding voyeurism. The two-year sentence would bring it in line with the maximum punishment for indecent exposure.

“Reports of cyberflashing are rising worryingly. This offence will close loopholes in the existing law and ensure that cyberflashing is treated as seriously as in-person flashing,” said Prof Penney Lewis, criminal law commissioner at the Law Commission, an independent body that reviews laws in England and Wales.

Other offences in the bill are designed to punish digital “pile-ons”, sending threatening social media posts and publishing hoax bomb threats. The offences, originally proposed by the Law Commission, are: sending or posting a message that conveys a threat of serious harm; sending a communication with the intent of causing psychological harm or serious emotional distress; and deliberately sending a false message with the intention of causing harm.

The online safety bill will contain substantial changes from its draft version when it is published this week. Alongside the new criminal offences, it will require that online platforms protect users from fraudulent adverts and will order commercial pornography sites to carry out age checks on people trying to access their content. Privacy campaigners have described the new age-verification policy as a “privacy minefield” and have warned that it could establish the principle of age-gating across the internet.

The bill will impose a duty of care on tech companies that host content created by internet users, with social media platforms a particular focus. The duty of care covers several areas including preventing the proliferation of illegal content and activity such as child sexual abuse and terrorist material, ensuring children are not exposed to harmful or inappropriate content, and protecting adults from legal but harmful content, such as cyberbullying.

Ofcom, the communications regulator, will oversee the legislation and will have the power to fine companies that breach the act up to 10% of global turnover.