A New York financial regulator said on Saturday it is investigating claims of gender discrimination by the new credit card from tech giant Apple and its issuer Goldman Sachs, after a cardholder's tweet about his wife's credit limit went viral.

American businessman David Heinemeier Hansson had tweeted on Thursday that the Apple Card is a “fucking sexist programme.” He said the card's “black box” algorithm had given him 20 times the credit limit of his wife, even though they file joint tax returns and she has a higher credit score.

Hansson tweeted a series of messages recounting fruitless chats with Apple customer service agents, who were unable to explain the disparity but blamed it on the algorithm that determines an applicant's credit-worthiness.

A “black box” algorithm refers to artificial intelligence systems whose decisions cannot be explained. In March, Apple started offering the Apple Card, issued by banking giant Goldman Sachs.

New York state regulators will “be conducting an investigation to determine whether New York law was violated and ensure all consumers are treated equally regardless of sex,” said a spokesman for Linda Lacewell, the superintendent of the New York Department of Financial Services.

“Any algorithm, that intentionally or not results in discriminatory treatment of women or any other protected class of people violates New York law.”

Goldman spokesman Andrew Williams said: “Our credit decisions are based on a customer's creditworthiness and not on factors like gender, race, age, sexual orientation or any other basis prohibited by law.”