The BBC has come in for a slew of criticism for broadcasting a program aimed at children as young as six, which tells the story of a school boy as he prepares to transition to a girl.

The program, broadcast on CBBC, follows a boy as he attempts to access drugs to delay the onset of puberty, as part of the process for having an eventual sex change, the Mail on Sunday has reported.

MPs and campaigners have questioned the appropriateness of telling such a story to young children, who may be easily confused by what they are watching. One mother, commenting on the program on the parenting site Mumsnet, said her daughter had questioned her gender identity and asked her “anxiously, if that means she was a boy”.

But the BBC has defended the show, insisting that it was merely trying to “reflect true life”. It said there was enough context for children to understand the theme.

Norman Wells, a family campaigner disagreed. He said: “It is irresponsible of the BBC to introduce impressionable children as young as six to the idea that they can choose to be something other than their biological sex.”

He added: “The more we promote the idea that a boy can be born into a girl’s body and a girl can be born into a boy’s body, and that drugs and surgery can put things right, the more children will become utterly confused. Respecting and preserving a child’s birth sex should be seen as a child protection issue.”

Conservative MP Peter Bone agreed, saying: “It beggars belief that the BBC is making this programme freely available to children as young as six. I entirely share the anger of parents who just want to let children be children.

“It is completely inappropriate for such material to be on the CBBC website and I shall be writing to BBC bosses to demand they take it down as soon as possible.”

Just a Girl depicts the fictional video diaries of a child who calls herself Amy and wears girls clothes, but explains to viewers that she was born as a boy, Ben, and is already in the process of halting puberty.

Some parents have been supportive – one Mumsnet user wrote on the site: “I don’t believe there is ‘too young’ for stuff like this. The earlier you teach your children that everyone is different and that nobody is ‘normal’ the better.”

But the row comes just a week after a judge found that a mother had been inflicting “significant emotional harm” on her seven-year-old son by forcing him to dress and act as a girl, which she believed he wanted. The boy was put into the care of his father and his father’s new partner, where he quickly reverted to displaying male tastes and behaviours.

Julian Brazier, Tory MP, told the publication: “This programme is very disappointing and inappropriate. Children are very impressionable and this is going to confuse and worry them.”

A BBC spokesman said: “Just A Girl is about a fictional transgender character trying to make sense of the world, deal with bullying and work out how to keep her friends, which are universal themes that many children relate to, and which has had a positive response from our audience.

“CBBC aims to reflect true life, providing content that mirrors the lives of as many UK children as possible.”