Gruffalo author Julia Donaldson has urged the new Culture Secretary to "show some leadership" and prevent cuts to libraries.
The writer, who was named Children's Laureate last year, told Maria Miller that cutting library budgets was "a false economy".
She will embark on a tour on Monday taking in 35 libraries across England, Wales and Scotland over six weeks to publicise her campaign.
In an open later to Ms Miller, who replaced Jeremy Hunt in the recent reshuffle, Ms Donaldson said: "I'm also hoping that the tour will draw attention to the erosion of the library service which is happening in so many local authorities, and to the current government's utter refusal to intervene or to provide any leadership."
Ms Donaldson, the best-selling author of more than 150 books including What the Ladybird Heard and Zog, said nearly 250 libraries were currently either under threat of closure or else have been closed or left council control since April.
She also said staff numbers had been cut along with the number of books available.
She added: "Children's use of those libraries which are still open has actually been rising over the last seven years, so please don't deprive them of the storytelling sessions, the homework clubs, the expert librarians and, above all, of the free books.
"Will you consider ring-fencing council spending on children's library services? Will you discuss with your colleagues the possibility of using some of the education budget for this purpose?
"Above all, will you (unlike your predecessor) respond to concerns and complaints, and show some leadership for our young readers?"