A handful of innocent-looking antique maps, one offensive word and tens of thousands of offended “untouchables” have plunged Google into an unspoken class war that has raged in Japan for centuries.

Despite its ambition to be the cartographer of the internet age, the search engine has lumbered into one of the darkest corners of Japan — the bigotry of mainstream Japanese society towards the burakumin, the “filthy mob”, whose ancestors fell outside the caste system of the 17th-century samurai era.

By allowing old maps to be overlaid on satellite images of Tokyo, Osaka and Kyoto on its Google Earth service, the search engine shows how the old ghettos relate to the 21st-century streets.

That, critics say, is perfect ammunition to hurt descendants of the people who lived there 400 years ago.

Under pressure to diffuse criticism, the search engine has asked the owners of the woodblock print maps to remove the legend that identifies the ghetto with an old term that translates loosely as “scum town”.

Google has unwittingly created a visual tool, however, that would have prolonged an ancient discrimination into the internet age, according to the lobbying group established to protect the human rights of three million burakumin.

Members of the sub-class were condemned by the old feudal system to unclean jobs associated with death and dirt. Laws made 150 years ago supposedly ended the caste system but, their descendants say, the prejudice remains.

Burakumin leaders said it was a discrimination that even its perpetrators could not explain adequately. In 2003 Taro Aso, the Japanese Prime Minister, dismissed the chances of Hiromu Nonaka — a burakumin who became Secretary-General of the ruling party — becoming Prime Minister. “There is no way we can make that kind of person prime minister,” Mr Aso was quoted as saying.

Companies sometimes hire private detectives to ensure that they are not employing someone of burakumin ancestry. Parents may run a similar check on their prospective son or daughter-in-law, and children may be excluded from good schools. Property prices in burakumin communities are lower than in the areas that surround them and public works projects take longer to be completed in the zones.

Toru Matsuoka, an opposition MP and member of the Buraku Liberation League, said that it amounted to illegal bullying.

“It is a discrimination that has driven many people to death. Two of my friends have killed themselves over this bigotry,” he said.

Throughout the recent history of the burakumin, the central issue has been identification. Because there is nothing physical to differentiate burakumin from other Japanese and because there are no clues in their names or accent, the only way of establishing whether or not they are burakumin is by tracing their family. By publishing the locations of the ghettos with the modern street map, the illegal quest to trace ancestry is made easier, Mr Matsuoka said.

He said that the mistake of Google was to believe the old maps had lost their capacity to cause offence.

Printing the maps is not illegal in Japan, but museums and publishers are careful about how they are presented, especially if the words on the maps may cause offence.

Yoshito Funabashi, a Google spokesman, said: “We had not acknowledged the seriousness of the map, but we do take this matter seriously.”

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