(Reuters) - Mastercard Inc and Visa Inc on Tuesday postponed plans to raise the fees U.S. merchants pay when customers use cards online until April next year, as businesses continue to struggle during the COVID-19 pandemic. “Mindful that some merchants are still facing unprecedented circumstances...we are delaying our previously announced interchange adjustments in the U.S. until April 2022,” Mastercard said. Interchange fee is the charge a merchant pays to the card-issuing bank every time a consumer swipes their card. Visa said in an email it would not make any future rate changes in the U.S. for another year while the economy recovers. Consumers have turned to online modes of payments, using cards to pay for clothes, food, groceries and even leisure spending as they shelter at home during the pandemic. Senator Dick Durbin, a Democrat from Illinois, and U.S. Representative Peter Welch, a Democrat from Vermont, wrote a letter here to Chief Executive Officers of Visa and Mastercard earlier this month, asking them to call off any plans to increase fees as the country was "still reeling from the ongoing pandemic". Bloomberg News had earlier in the day reported both Visa Inc and Mastercard had postponed plans to hike card fees until April 2022. (bloom.bg/30OF0C9)