Copies of Chris Riddell’s picture book about a friendly blue monster who lives under a little boy’s bed, Mr Underbed, have sold out in the days since the former children’s laureate accused John Lewis of “help[ing] themselves” to the story for their Christmas TV ad.

Riddell pointed out the similarities between his debut picture book, which was published in 1986, and John Lewis’s commercial, which features the monster Moz, last Thursday. “John Lewis help themselves to my picture book,” tweeted Riddell, adding: “The idea of a monster under the bed is by no means new but the ad does seem to bear a close resemblance to my creation – a big blue unthreatening monster who rocks the bed and snores loudly.”

He has since added: “I think it’s important for creative people to get the recognition for the work they do. When one is influenced by something, it’s good to acknowledge that.”

Riddell’s publisher, Andersen Press, said on Monday that it had sold out of its stock of Mr Underbed overnight on Thursday, and has now ordered a new print run, which will arrive on 29 November. “The response on Twitter has been incredible, with lots of retailers looking to get stock, or promoting the stock they had over the weekend. We already have orders waiting on our system for the reprint,” said a spokesperson. “It seems that as the Moz the Monster book is exclusive to John Lewis stores, everyone else is looking for a slice of the pie with Mr Underbed.”

Andersen is also planning a campaign “seeking justice” for Mr Underbed. The publisher said that in what it dubbed “the Battle of the Monsters”, Mr Underbed will face off against Moz the Monster – the book version of John Lewis’s ad published by Nosy Crow. “The characters [will] go head to head, with the goal of seeing who wins in the charts,” said Andersen, which is launching an illustration competition for the public to design their own monster, with the winner to have their picture recreated by Riddell.

Klaus Flugge, founder of Andersen Press, said: “We couldn’t believe the similarities when Chris showed them to us. We want our very own Mr Underbed to beat the competition in the charts this Christmas with our campaign that is available to ALL retailers. Stock is on its way and we are ready for battle.”

Riddell wrote in the Observer on Sunday that the response to his complaints about the John Lewis ad had been overwhelming. “My fellow children’s book illustrators and writers have been outraged on my behalf, for which I heartily thank them. Talk of legal action has flooded my Facebook feeds, but I won’t be pursuing that,” he said. “Instead, I hope that advertising agencies, and the big companies they work for, take care to credit creative people whose work they might reference. We have the finest children’s book writers and illustrators in the world – their work should be cherished and credited properly.”

A spokesperson for John Lewis said last week: “The story of a big hairy monster under the bed which keeps a child from sleeping is a universal tale that has been told many times over many years. Ours is a Christmas story of friendship and fun between Joe and Moz the Monster, in which Joe receives a night light that helps him get a good night’s sleep. The main thrust of our story is utterly different to Chris Riddell’s.”