Secondhand booksellers across the United Kingdom and Ireland are reporting a surge in bulk orders from unidentified buyers, fuelling speculation that AI companies may be purchasing books to obtain data for training artificial intelligence systems.

Bookshops contacted by the Guardian said they had received orders from buyers in the US, Canada, continental Europe and the UK. Similar trends have also been reported by booksellers in the US, Australia and other parts of Europe.

Stuart Manley, co-owner of Barter Books in Alnwick, Northumberland, said the unusual orders began arriving about three months ago. He noted that, unlike typical bulk purchases, the books were not organised around specific themes such as sport or motoring.

“It’s definitely a strange combination of books,” said Manley. “Normally a book order is on a theme but this is all over the place.”

A recent order at Barter Books included an Estonian translation of John le Carré’s The Mission Song, a specific edition of Anne Brontë’s Agnes Grey and the October 1983 issue of Warship, a monthly magazine.

Manley said he had sold “hundreds” of randomly selected books to three buyers, generating about £4,000 in total.

Jim Shaughnessy, owner of MW Books in Claregalway, Ireland, said his shop had also been receiving large and diverse orders since May.

“They are sporadic, presumably machine-driven and have little in terms of thematic currency; books on agricultural implements in 18th century Africa through to biographies of 1950s racing car drivers,” he said. “Personally, I don’t see we have the right to dictate what any customer does with their purchases but it is more than curious to see what’s being selected.”

David Gower-Spence, owner of BookLovers of Bath, said his business experienced a surge in orders between May and July, with buyers purchasing about 200 books.

The Washington Post reported this year that Anthropic, the AI company behind the Claude chatbot, had spent tens of millions of dollars acquiring books, removing their spines and scanning their contents before sending the books for recycling.

Anthropic said: “Claude is trained on a mix of publicly available web data, commercially acquired datasets, and data we generate ourselves. Sourcing books is a widely used approach for training large language models across the AI industry. None of our data acquisition programs buy and destroy rare or antiquarian books.”