Super realistic masks are made from flexible materials such as silicone and are designed to imitate real human face- down to every last detail.

In a study by the Universities of York and Kyoto, researchers asked participants to look at pairs of photographs and decide which showed a __26__ face and which showed a person wearing a mask.

Surprisingly, participants made the wrong call in one-in-five cases.

The 20% error rate __27__ in the study likely underestimates the extent to which people would struggle to tell an __28__ face from the real thing outside of the lab.

The researchers collected data from participants from both the UK and Japan to __29__ any differences according to race. When trial participants were asked to choose between photographs of faces of a different race from theirs, response times were slower and selections were 5% less __30__ .

There are now dozens of criminal cases in which offenders have __31__ themselves off as people of a different age, race or gender, sending police investigations down the wrong path.

In one recent case, an international gang used an __32__ realistic mask to pose as a French minister, __33__ business executives out of millions of pounds.

Dr Jet Sanders, who worked on the study while a PhD student at the University of York, said: "Failure to detect synthetic faces may have important implications for security and crime prevention as super realistic masks may __34__ the key characteristics of a person's appearance to be __35__ identified."