Thousands of online and mail order retailers have been hit by technical problems at payment service provider Protx.

The BBC reports that sites were left unable to receive payments today after an upgrade at the company went wrong.

The problems apparently began at 6am, but had been solved by 2.30 pm, according to a Protx spokesperson.

“We apologise wholeheartedly for the performance… throughout the morning and afternoon,” the firm said.

Protx manages credit and debit card payments for around 10,000 retailers.