Initially scheduled for introduction on 14 September 2019, the rules - which demand a two-step verification process for all online purchases over EUR - have suffered a series of rolling setbacks amid mounting pressure from merchants and payments players.

In a statement, the FCA says: "This further 6-month extension is to ensure minimal disruption to merchants and consumers, and recognises ongoing challenges facing the industry to be ready by the previous 14 September 2021 deadline. The new 14 March 2022 deadline is the latest we expect full SCA compliance for e-commerce transactions.

"We previously agreed to give firms extra time to implement SCA for card-based e-commerce transactions in response to concerns about industry readiness, and to limit the impact on consumers and merchants. We also provided an additional 6-month extension in response to the coronavirus crisis.

"We welcome the implementation of SCA solutions which protect consumers while minimising the potential for disruption to customers and merchants.

"We still expect firms to continue to take robust action to reduce the risk of fraud."

Across Europe, where the rules have already been enforced, ecommerce merchants in France and Spain have experienced on average a 25% reduction in conversion rates, a 30% reduction in Germany, and up to 40% of transactions are being lost in Italy, costing merchants millions of Euros per month.

Galit Michel, VP of payments at Forter, says: "Across the board, merchants are struggling to manage the significant changes to their payments process, and we have observed a lack of issuer readiness, as well as low levels of customer co-operation with the increase in friction at the checkout. The desired impact of PSD2 was to reduce levels of fraud, but in reality, the outcome has been to frustrate customers and deprive merchants of much-needed revenue.