The consumer champion carried out an investigation into 111 major retailers and found that deferred payment options advertised in-store often included little or no information about late fees, credit checks and the risk of falling into debt.

Which? focused on the fashion, baby and child, and homewares sectors to find out how they present BNPL as shoppers browse a site and make a purchase.

More than half (62 out of 111) of the online retailers Which? analysed offered at least one BNPL scheme at the checkout, and nearly 70% of those that offered a pay later service had more than one option available.

JD Sports offered the most schemes, listing six options at the checkout including Klarna pay in 30 days, Klarna pay in 3, Clearpay, Laybuy, Openpay and Zip.

Of the retailers that offered BNPL, nearly nine in 10 (87%) promoted the schemes on their product pages, while three in 10 (30%) featured ads for BNPL on their homepages.

An expert in marketing and behavioural sciences told Which? these promotions can encourage shoppers to buy more and that reframing a large expense as a small daily or monthly expense can distort how we understand the cost of a product.

Which? found nine retailers, the majority of which sell baby and children’s products, that didn’t include any information at all about late fees on their checkout, product listing or BNPL explainer pages for certain BNPL providers. These retailers include Baby and Child Store, Bella Baby, Cosatto, Footasylum, Huggle, Kiddies Kingdom and Natural Baby Shower.

Which? warned that failing to clearly communicate the risks of using a BNPL scheme could land customers with unexpected fees. It could also leave them unaware of some of the potential consequences of failing to keep up payments such as a negative impact on your credit score or having the debt referred to a debt collector.

Klarna, Laybuy and Clearpay all have guidelines they share with retailers on how their products should be presented, but Which? found some retailers were not adhering to them.

Which? wants the BNPL sector to be regulated to ensure greater transparency on fees, credit checks and repayments.

Gareth Shaw, Which? head of money, said: “While BNPL services offer convenience at the checkout, our research shows that online shoppers are being bombarded with these schemes at the biggest retailers, often with no information or warnings about the risks of late fees or getting into debt. Failing to communicate these risks could land customers with unexpected charges or impacted credit scores.

“This demonstrates why there should be no further delay to plans for BNPL regulation, which should include much greater marketing transparency, information about the risks of missed payments and credit checks before consumers are cleared to use BNPL providers.”