TOKYO • Japan's toilet chiefs say they have come up with a plan to stop tourists getting their knickers in a twist over the country's mind-bogglingly high-tech loos.

Under new guidelines, manufacturers will use the same eight pictograms to tell users which button flushes, which one fires a frighteningly accurate jet of water at the backside and what to press to close the lid.

The standardised icons will appear on toilets sold in Japan from April, according to Jiji Press.

The decision to create standardised pictograms came after a 2014 survey found that a quarter of 600 foreign visitors said they could not understand some of the symbols that appear on the toilet buttons.

The Japan Sanitary Equipment Industry Association hopes that ensuring all toilets have standardised images will prove just the job, ensuring millions of non-Japanese speaking visitors know the difference between a big and a small flush.

Japan's most state-of-the-art toilets offer everything from seat- warming and bidet functions to motion sensors, variable jet strengths and powerful deodorisers.

Celebrities such as Madonna, Leonardo Di Caprio and Will Smith have raved about the smart loos, which are a big hit among tourists, particularly the Chinese.

But there has been no standardised set of symbols for their many buttons and different manufacturers often use their own images, representing something of a pain in the backside for unaccustomed users.

Among the eight drawings are what looks like a woman sitting on a fountain for bidet function, a pair of splayed cheeks being sprayed with water for backside wash and something resembling a tornado for a big flush.

Japan has been drawing record numbers of tourists in recent years and Tokyo is expecting millions of visitors when it hosts the Olympic Games in 2020.

Last month, Japan's Narita international airport made global headlines after introducing "toilet paper" for germ-infested smartphone screens in its toilets.

AGENCE FRANCE-PRESSE