One of Japan’s most famous hot springs – usually a place for a contemplative soak in mineral-rich waters – has been closed indefinitely following complaints that groups of bathers were regularly using it for orgies, footage of which has been posted online.

The hot spring, or onsen, tourism association in Shiobara, Tochigi prefecture, near Tokyo, said it had closed Fudo no Yu, an outdoor bath that was popular for its mixed bathing and panoramic views.

What the outdoor onsen lacks in size – the circular bath is just three metres (nine feet) in diameter – it makes up for in atmosphere.

Only about 10 people can bathe comfortably at any one time, but it draws large numbers of visitors hoping to relax in its mountain forest setting.

However, the bath’s secluded location encouraged exhibitionists, who took advantage of the absence of a caretaker and its policy of collecting a modest 200 yen admission fee through an honesty box, according to Japanese media reports.

Local residents and other bathers had been complaining about witnessing lewd acts for about a year, but the last straw appeared to have been a succession of weekend orgies involving as many as 15 middle-aged men and several younger women, according to the Tokyo Reporter website.

The bath, part of the popular Shiobara onsen resort, is also thought to have been targeted by voyeurs armed with cameras, the site said, citing a report in the Mainichi Shimbun.

Shigeki Tashiro, the head of the local council, said action had to be taken to safeguard Fudo no Yu’s reputation as one of Japan’s finest onsen.

“With the resort being promoted by the prefecture as a tourist attraction, it was a tough decision,” Tashiro was quoted as saying. “However, if left as it is, the image of the area as a tourist destination could be downgraded.”

Onsen are an important part of the tourism economy in Japan, whose vast reservoirs of geothermal activity support more than 3,000 hot springs.

Fudo no Yu’s popularity as a location for al fresco sex has embarrassed local tourist authorities, which had featured it on their website and promotional posters.

“We are sorry, but it was breach of manners that was impossible to overlook,” an unnamed member of the local residents’ association told the Asahi Shimbun. “We had no choice but to close the bath.”

The offending onsen, which has now been drained of its water, has existed since the Meiji era (1868-1912), media reports said.

