A sex education kit for primary school aged children which includes models of male and female sex organs has sparked a storm of controversy in Switzerland.

Daniel Schneider, a deputy kindergarten rector for Basel who helped develop the programme, said: “Children should be encouraged to develop and experience their sexuality in a pleasurable way”.

The kit, which was being called a “sex box” before thousands of parents protested, is to be used as part of a radical new sex education programme for primary school aged kids in Basel.

A teachers’ guide says that teachers should “show that contacting body parts can be pleasurable”.

It also suggests that they should get pupils to massage each other or to rub themselves with warm sand bags, all accompanied by soft music.

Materials for the programme include a teachers’ guide, dolls, puzzles and books for four- to ten-year-olds, and a box with the more explicit materials for older children.

After receiving some 3,000 letters of complaint from parents, officials in Basel have decided to rename the “sex box”.

Christoph Eymann, Basel education minister, said: “It was no doubt stupid to call it a ‘sex box’ – we will change that.

“But we will stick to our goal: to get across to children that sexuality is something natural. Without forcing anything upon them or taking anything away from their parents”.

Some parents have called for their children to be exempted from the controversial lessons, but Mr Eymann is opposed to such a move.

He has, though, ordered the contents of the box to be examined after finding the cover of previous teaching material tasteless.

In March an MP said that sex education resources in Britain should be licensed to ensure they are age-appropriate, following concern among parents about “inappropriate” materials.