The results suggest that real humans can easily fall for machine-generated faces — and even interpret them as more trustworthy than the genuine article.

“We found that not only are synthetic faces highly realistic, but they are also more trustworthy than real faces", says study co-author Hany Farid, a professor at the University of California, Berkeley.

The first group did not do better than a coin toss at telling real faces from fake ones, with an average accuracy of 48.2 percent... The group rating trustworthiness gave the synthetic faces a slightly higher average rating of 4.82, compared with 4.48 for real people.

Study co-author Sophie Nightingale Study said participants did overwhelmingly identify some of the fakes as fake.

"We're not saying that every single image generated is indistinguishable from a real face, but a significant number of them are."

The authors of the study end with a stark conclusion after emphasising that deceptive uses of deepfakes will continue to pose a threat: "We encourage those developing these technologies to consider whether the associated risks are greater than their benefits", they write.

"If so, then we discourage the development of technology simply because it is possible."