Natwest's computer systems experienced problems that lead to service outages, according to reports by bloggers and Twitter users.
Dan Stuchbury, a developer who lives in Wiltshire, blogged on Friday that he had been told at his local Natwest branch that their computer systems had crashed.
Twitter user Gavin Quayle said that Natwest ATMs across London were also not working. Other Twitter users reported that RBS machines were also down (Natwest is owned by RBS).
A Natwest spokesperson told ZDNet UK on Friday that there had been an internal technical problem with Natwest's systems, and that no outside hack had caused the outage.
"There was a technical issue impacting some of our systems for a short period of time this morning," said Natwest in a statement. "We quickly identified and resolved the issue and we apologise for any inconvenience this may have caused our customers."
The outages lasted for approximately an hour, said the spokesperson.
While the issue affected all Natwest branches in the UK, no RBS bank machines had been affected, the spokesperson added.