The UK restaurant chain Dishoom has appealed for readers to buy their eponymous cookbook or donate to charity, after a pirated version went viral and was sent to “everyone and their nice auntie”.

The chain published its first recipe book last September, with recipes for “Bombay comfort food” including a bacon naan roll, okra fries and black daal, as well as stories and photographs of the Indian city.

But Dishoom announced on Twitter earlier this week that “some cheeky so-and-so” was sending out illegal pdfs.

“It’s what you might call an act of piracy,” said the restaurant. “I guess this piracy feels a touch harder during these tricky times when restaurants have no people in them.”

Co-founder Shamil Thakrar, one of the book’s three authors, said that many people “assumed that we released this digital copy for free. It seemed to make sense to acknowledge that the copy was out there and that it was indeed a pirate copy, and to encourage people to buy the real thing.”

Dishoom is closed to the public because of the coronavirus pandemic, and contributing to the Feed NHS project, which delivers hot meals to hospitals. Readers who have come across the pirate copy were urged to give to the charity Hospitality Action. The chain also asked readers to send a link to their appeal back up the chain to whoever is distributing the pirated copy.

Readers from far and wide have responded by buying copies for friends and families, Thakrar said, with the charity reporting “some kind donations” as well.

“This might sound a bit old-fashioned,” Thakrar said, “but there really is nothing quite like settling down with a weighty volume to immerse yourself in the stories contained in it, not to mention the joy of owning a well-loved, much-thumbed cookery book – annotated, corners folded on firm favourites, pages carrying the marks of many hours happily spent in the kitchen.”

According to publisher Bloomsbury, the cookbook has sold almost 100,000 copies to date, and was No 13 in the hardback nonfiction charts last week. It has been described as “a total delight” by Nigel Slater, who said he had “never read a book that has made me look so longingly at my suitcase”.

Bloomsbury said it took copyright infringement extremely seriously, and had been in close touch with the restaurant and its authors since it became aware of the piracy.

“[We] have taken all the steps we can to address it,” the publisher said. “We have contacted and issued takedown notices to the relevant platforms and we conduct our own sweeps for piracy sites.”

The restaurant was more understanding on Twitter, acknowledging that those who could neither afford to buy the book nor donate to charity should just enjoy the pirated copy.

“We do appreciate that some people who have been sent the pdf aren’t perhaps in a position to purchase the cookery book, especially in these tough times,” said Thakrar, “and we do genuinely hope they’ll enjoy it. And we can take some pleasure too in knowing it has brought comfort to people.”

• This article was amended on 15 May 2020. Dishoom has a long-established link with the charity Magic Breakfast, which has seen more than 8m meals donated to children who would otherwise go hungry. This was wrongly attributed to Hospitality Action and has now been corrected.