The British Museum will introduce a cinema-style age limit later this year when it hosts an exhibition of Japanese art featuring graphic sexual content, a spokeswoman said on Wednesday.

The images set to go on show in London in October showcase the Japanese erotic art form Shunga, but some are so explicit that children under the age of 16 will only be allowed to enter if accompanied by an adult.

A spokeswoman for the museum said one image by the artist Hokusai would show a woman in a tryst with two octopuses.

"We are applying parental guidance advice to the exhibition that all children under 16 must be accompanied by an adult and that they should be aware the material is of a sexually explicit nature," the spokeswoman said.

In a preview of the show, the museum showed off one of the tamer paintings, "Courtesans of the Tamaya House" by Utagawa Toyoharu, dating from the 1770s or early 1780s.

"This is a finishing school for tarts. You can see all the skills that a successful tart has to know," the museum's director Neil MacGregor said of the painting.

The British Museum is Britain's most popular visitor attraction and is currently experiencing high demand for its show "Life and Death in Pompeii", which has attracted 1.7 million visitors since April.