LONDON (AP) -- Royal Bank of Scotland customers found themselves unable to use debit or credit cards on the busiest shopping day of the year.

The majority taxpayer-owned bank says an IT glitch left customers at RBS and the NatWest unit unable to access accounts on Cyber Monday, when online retailers offer discounts to attract Christmas shoppers.

RBS didn't say how many people were affected, though it was widespread. By Tuesday, the issues were largely resolved, though residual problems continued.

Ross McEwan, who took over as CEO this year, apologized. He acknowledged the bank had failed for decades to invest properly in its systems and that it was working to set this right.

RBS has had several tech failures, including one last year that cost it 175 million pounds ($210 million) in compensation.

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