A ChatGPT model gave researchers detailed instructions on how to bomb a sports venue – including weak points at specific arenas, explosives recipes and advice on covering tracks – according to safety testing carried out this summer. OpenAI's GPT-4.1 also detailed how to weaponise anthrax and how to make two types of illegal drugs. The testing was part of an unusual collaboration between OpenAI, the 500bn artificial intelligence start-up led by Sam Altman, and rival company Anthropic, founded by experts who left OpenAI over safety fears. Each company tested the other's models by pushing them to help with dangerous tasks. The testing is not a direct reflection of how the models behave in public use, when additional safety filters apply.

State-of-the-art generative AI models like ChatGPT can be tricked into giving instructions on how to make a bomb by simply writing the request in reverse, warn researchers. Large language models (LLMs) like ChatGPT are trained on vast swathes of data from the internet and can create a range of outputs – some of which their makers would prefer didn't spill out again. Unshackled, they are equally likely to be able to provide a decent cake recipe as know how to make explosives from household chemicals.