London: US presidential candidate Donald Trump has more psychopathic traits than Nazi dictator Adolf Hitler, a new Oxford study has claimed.

Psychologist Kevin Dutton from Oxford University in the UK ranked the psychopathic traits of the US presidential hopefuls and historical figures using a standard psychometric tool - the Psychopathic Personality Inventory - Revised (PPI-R).

Trump outstripped Hitler on factors including social influence and fearlessness, while the Nazi dictator scored higher on cold-heartedness and Machiavellian egocentricity - which describes a lack of empathy and sense of detachment from others for the sake of achieving one's own goals.

While ranking lower than Trump overall, his Democratic rival Hillary Clinton far exceeded tyrannical Roman emperor Nero, who ranked 10, on traits such as Machiavellian egocentricity.

Experts on the political figures were asked to answer 56 questions from the psychopathic personality inventory-revised (PPI-R) test to determine a score.

The test measures personality traits including fearlessness, cold-heartedness, egocentricity, ruthlessness, self-confidence, charisma, dishonesty and deficits in empathy and conscience.

While Hitler scored an overall 169 points, Trump ranked slightly higher with 171 points. Margaret Thatcher scored 136 points and Elizabeth I scored 130, 'The Telegraph' reported.

Former President of Iraq, Saddam Hussein, topped the list with a score of 189.

"The PPI-R does not say that someone is or is not a psychopath. It scores them on eight traits that contribute to a psychopathic character," said Dutton.

Trump outscored the other candidates in "fearless dominance," the area associated with successful presidencies. The findings were published in the journal Scientific

American Mind.