One of Britain's biggest banks is embroiled in a mis-selling scandal over "buy now, pay later" loans.

An internal investigation into Barclays Partner Finance (BPF), the consumer lending arm of Barclays Bank, reportedly identified a lack of supervision over retailers offering credit for purchases including cars, furniture and home improvements.

This potentially meant consumers were saddled with debt they could not afford to repay or that vulnerable people were subjected to pressure tactics by salesmen.

The Financial Conduct Authority (FCA) asked the banking giant to overhaul its lending practices when it learnt of the shortcomings, which were set out in a report from 2016.

A spokesman said it expected firms to offer "redress when appropriate" and it would "take appropriate action" if this did not happen.

The investigators' findings included an alleged failure to effectively scrutinise some credit agreements - which allow customers to pay for an item over a prolonged period - paving the way for loans to be sold in a misleading or highly pressured way.

Five firms selling BPF loans reportedly had more than one in 10 customers in arrears for their monthly repayments.

Another retailer had more than half of its customers falling behind on their debts, according to the report.

Cases flagged to investigators included one customer with learning difficulties who was pressured into taking out a loan and another who was sold "free credit" that actually carried 28.9% interest, it was reported.

A Barclays spokeswoman said: "Since commissioning this report in 2016, we have maintained an open and cooperative dialogue with the FCA, and have taken significant steps to review and improve our systems, processes and training to ensure that we meet our regulatory obligations and policy commitments.

"Where any customer detriment is discovered, we will act swiftly to identify and fix the root cause, and learn how we can prevent it from happening again."