LONDON — The Royal Bank of Scotland said on Wednesday that about 600,000 customer transactions had not been processed as a result of a technology failure overnight. The issue affected transactions at the company’s R.B.S., National Westminster Bank, Coutts and Ulster Bank brands.

“We are aware of an issue which has resulted in a delay to payments and direct debits being applied to some customer accounts,” an R.B.S. spokesman said. “We have fixed the underlying issue, we apologize for the inconvenience caused, and we are working flat out to get these payments updated for our customers no later than Saturday.”

The spokesman added, “We will ensure no customers are left out of pocket as a result of this issue.”

The disruption is one of several embarrassing technology problems for R.B.S. in recent years.

The lender was fined 56 million pounds, or about $87 million, by British regulators last year over a technology failure that left millions of customers unable to access their accounts for several weeks in 2012.