Bestselling teen author Juno Dawson is in dispute with a Catholic secondary school that she believes banned her from speaking because she is transgender.

The writer, known for her novels This Book Is Gay and Mind Your Head, was due to visit the school in Lancashire to talk about her latest release, Margot And Me, when the school abruptly cancelled the visit with less than 48 hours' notice, Buzzfeed reported.

A staff member informed an event rep that the visit would have been "inappropriate".

Brownedge St Mary's Catholic High School said that the visit was postponed rather than cancelled, but the author insisted no one has been in touch with her to reschedule.

She said the book, about a granddaughter and her grandmother in World War II, was "perfectly appropriate" for the year seven and eight pupils, and that she had spoken about it in "a mixture of grammar schools, private schools, faith schools, all sorts of different schools."

The school had previously been commended as a Stonewall champion, a status which recognises an institution's work on support and advocacy of LGBT issues.

"I asked for the visit to be postponed to a later date, not cancelled," said headteacher Martin Reynolds in a statement. "We would never discriminate against any individual on the grounds of sexual orientation or gender identity as we teach our children that each individual person is precious and unique."

"A representative said she felt the subject matter meant that a visit was inappropriate at this time because we wanted a proper context for it so that our younger students could get more value out of it. … We wanted more time to do this theme justice for our younger students," he added.

Dawson has denied the claim: "There will be young people at Brownedge who will be LGBT. Those kids knew I was coming and now I'm not. It beggars belief. One does wonder what kind of support those kids are getting."

Dawson wrote about her transition in a column for Glamour. In her first piece about the process, she said: "All I or any trans woman wants is to be taken seriously and accepted. We want to be believed."