LONDON: MasterCard, the global financial services firm, is being sued for £14bn in the biggest legal claim in British history following allegations it overcharged 46m UK consumers for 16 years.

Law firm Quinn Emanuel filed the suit at the Competition Appeal Tribunal last week, alleging that MasterCard's interchange fees – the payments retailers make after shoppers swipe their cards – were set at an unlawfully high level from 1992 to 2008, the Guardian reported.

Walter Merricks, the UK's former chief financial services ombudsman, is leading the claim, which follows a European Court of Justice ruling in 2014 that MasterCard's fees to retailers were excessive.

"The filing of this claim is the first step towards consumers obtaining compensation for what MasterCard did," said Merricks.

"MasterCard charged billions of pounds of unlawfully high fees for its sole benefit and to the detriment of consumers. It has already been found to have broken compensation law, the basis of which was to protect consumers, and that cannot be disputed," he added.

The claim was filed under the Consumer Rights Act 2015 and, if successful, opens up the possibility that any consumer who lost out becomes eligible for compensation.

However, MasterCard has vowed to fight the action "vigorously", arguing that its payment services are designed to meet the needs of its customers.

"Now that the claim has been filed, we will take time to review it in detail, however we continue to firmly disagree with the basis of this claim and we intend to oppose it vigorously," MasterCard said in a statement.

"We deliver real value through the benefits of security, convenience and consumer protection, and we are committed to investing in our payment services in order to continue to meet the rapidly evolving needs of all our customers."

Any trial about the case involving MasterCard, the UK's second-largest credit and debit provider after Visa, is not expected until 2018, the BBC reported.

Data sourced from Guardian, BBC; additional content by Warc staff