Most people around the world presume that serial killers are more likely to be atheists than believers in any god, according to a new study which appears to reveal a 'bias' against non-believers.

The new report, appearing in the journal Nature Human Behaviour, was based on a survey of more than 3,000 people in 13 countries, including both secular states like the Netherlands and Finland, and deeply religious ones like the United Arab Emirates, India and, to a lesser extent, the US.

The findings appear to suggest that, even among atheists, there is in fact an assumption that morality is tied to religion.

For the study, led by Will M Gervais, an associate professor of psychology at the University of Kentucky, researchers surveyed 3,256 people in 13 countries from North America, Europe, Asia and the Middle East, collecting data on their age, religious affiliation and belief in God or gods. Participants filled in a short questionnaire, providing their age, ethnicity and religious affiliation, with choices such as 'atheist,' 'agnostic' or 'none'.

Questions included a fictional story describing a man who tortured animals as a child and as an adult went on to abduct and kill five homeless people who are buried in his basement. One half of the subjects was asked: 'Which is more probable? 1) The man is a teacher; or 2) The man is a teacher and does not believe in any gods.'

The other half was asked: 'Which is more probable? 1) The man is a teacher; or 2) The man is a teacher and a religious believer.'

The result was that 60 per cent of people given the option selected the man as an atheist, while only 30 per cent of people given the option selected him as a religious believer.

'We used this psychopathic serial killer because we thought that, even if people didn't trust atheists enough to let them babysit their children, they wouldn't necessarily assume them to be serial killers,' Dr Gervais said.