Ryanair has rejected what it calls “false claims” made by lastminute.com in a dispute over customer refunds.

The online travel agent was last week threatened with legal action by the Competition & Markets Authority (CMA) having failed to meet a deadline to return cash to customers by the end of January.

While apologising, lastminute.com also argued Ryanair was partly to blame as the airline had told customers to contact it direct for refunds.

The company said this has created confusion, as it does not know which package holiday customers have asked or received a refund from Ryanair directly.

However, Ryanair said it has no commercial agreement with lastminute.com, and argued the company overcharges customers and provides it with “fake contact and payment details”.

The carrier said consumers should always book directly on the Ryanair website to ensure a reliable customer service and speedy refunds when travel plans are disrupted.

A spokesperson for Ryanair said: “We welcome the CMA ruling which exposes the unlawful actions carried out by lastminute.com, who have been blocking refunds from thousands of customers for months.

“Customers would not be waiting to be reimbursed if lastminute.com did not change customer contact and payment details at the time of booking, a practice by online travel agencies to prevent customer awareness of overcharging of up to 70 per cent versus booking direct.”

To assist customers affected, Ryanair launched a customer verification form in July, which enables customers to apply for a refund directly from the carrier.

“We have done everything we can to assist online travel agent customers who have been disrupted by these anti-consumer practices and we call on the CMA to ensure lastminute.com and other similar third-party travel websites provide correct customer contact and payment details at the time of booking.”