My Friend Cayla is like a real friend, according to the manufacturer’s website. In Germany, however, her cover has been blown.

The blonde doll, who answers “tricky questions about things like animals, countries and famous people” is accused of being a spy. She can be hacked and used as a surveillance tool, says the Bundesnetzagentur, the German telecoms agency.

Any device with “concealed” eavesdropping powers is illegal in a country with some of the world’s toughest privacy laws introduced in reaction to snooping by the Nazis and the Stasi.

Children’s intimate chats with their real friends and adult conversations within range of its microphone could be picked up by bluetooth, so Cayla has been banned in Germany and anyone caught selling her faces a €25,000 fine.

The agency has no plans to recall the dolls but “assumes that parents will take it upon themselves to make sure the doll does not pose a risk”. For some paranoid Germans that could mean taking a hammer to her.

The doll is made by Genesis Toys, a US company. It is sold in Britain by Vivid Toy Group for £49.99 and is also on sale in other European countries. Vivid Germany, the distributor, said that it would challenge the decision because it did not accept that the doll broke the law. “There is no reason to destroy Cayla or give the doll away,” the company said. “It is not a spying device.”