Liza Minnelli fans who bought signed copies of her memoir are seeking refunds because they believe her signature is fake.

Copies of Kids, Wait Till You Hear This ! by the American 80-year-old singer were marketed around the world as “hand-signed collectibles”, with premium editions costing up to $250 (£185).

However, some buyers have questioned the uniformity of the signatures and speculated that they were digitally signed by an autopen , a device that replicates handwriting.

“When you see footage of Liza today in her own documentary, she is far too frail to have signed a handful of books this accurately, let alone hundreds,” said autograph collector Gareth Brown, who contacted the Guardian after paying £25 for a signed copy in a Kent bookshop.

Copy of Liza Minelli’s memoir bought by Gareth Brown.…