Maria Julia Assis was sitting down to a meal in her terraced home in north London when her 6-year-old son ran into the dining room, his face pale.

The puzzle game on his Android phone had been interrupted by a video showing Hamas militants, terrified Israeli families and blurred graphic footage. Over a black screen, a message from the Israeli Ministry of Foreign Affairs told the first grader: "WE WILL MAKE SURE THAT THOSE WHO HARM U.S. PAY A HEAVY PRICE."

Assis, a 28-year-old barista from Brazil, said that the ad left her son shaken and she quickly deleted the game.