The UK government has announced plans to enforce legislation requiring Apple Inc. (NASDAQ: AAPL) and Alphabet Inc.’s Google (NASDAQ: GOOGL, NASDAQ: GOOG) to block explicit images on children’s smartphones. The decision follows unsuccessful talks with the tech giants regarding voluntary safety measures.

According to UK Secretary of State for Digital, Culture, Media and Sport Lisa Nandy, the government will commence work on an act of Parliament aimed at preventing under-18s from taking, sharing, or viewing explicit content on their devices. Nandy stated that the three-month deadline for talks with Apple and Google had passed, though she noted the companies could still reach an agreement. She emphasized that it was “almost certain” that unprecedented legislation would be needed.

Prime Minister Andy Burnham added that these protections would be “built into the device and switched on by default.” The mandate requires tech companies to verify an adult user’s age before allowing them to view or send explicit content. The government also intends to extend these restrictions to children’s apps, which would require additional legislation.

The move follows a June announcement by former Prime Minister Keir Starmer, who gave Apple and Google until September to introduce technology blocking children from viewing, sharing, or taking sexually explicit images. Failure to comply could trigger legislation with fines and criminal liability. Apple and Google did not immediately respond to a request for comment.

Criticism of the proposal has come from various quarters. Billionaire Elon Musk called the policy a “wolf in sheep’s clothing,” suggesting the real goal was to track individuals until they verify their identity. YouTube spokesperson Jay Stoll similarly argued that blanket bans could push children toward “anonymous, less-safe services.”