WASHINGTON (AFP) - More than one-in-four adults harbour anti-Semitic attitudes and barely half worldwide have heard of the Holocaust, according to a global study released Tuesday by a major Jewish rights group.

The US-based Anti-Defamation League, in a survey of 53,100 adults in 102 countries and territories, "found that anti-Semitic attitudes are persistent and pervasive around the world."

The ADL, which fights anti-Semitism, says that 26 per cent of those surveyed - equivalent to an estimated one billion adults around the world - expressed anti-Semitic attitudes and opinions.

And it found two out of three people surveyed have either never heard of the Holocaust - the World War II massacre of Jews led by Nazi Germany - or do not believe historical accounts to be accurate.

"For the first time we have a real sense of how pervasive and persistent anti-Semitism is today around the world," said Abraham Foxman, ADL National Director.

"The data from the Global 100 Index enables us to look beyond anti-Semitic incidents and rhetoric and quantify the prevalence of anti-Semitic attitudes across the globe.

"We can now identify hotspots, as well as countries and regions of the world where hatred of Jews is essentially non-existent."

Respondents were asked 11 questions based on age-old stereotypes about Jews, including classical stereotypes about Jewish power, loyalty, money and behavior.

Those who responded affirmatively to six or more negative statements about Jews were considered to hold anti-Semitic attitudes.