A power outage at a Google Cloud data centre near London caused serious failures to services on Tuesday, leading to widespread disruptions for several UK banks.
Google said in a service health update that most services had returned to normal by 1210 GMT, six hours after the incident began.
"We are seeing the recovery of services for most workloads in europe-west2," the US tech giant said, referring to its London data centre.
Google said its cloud services suffered an outage "due to a power event", in an incident that began at 0608 GMT.
Services for the digital bank Revolut, including withdrawals from ATMs, bank transfers and bank card top-ups, were disrupted, which a source close to the matter attributed to the Google Cloud failures.
UK lenders Lloyds and HSBC confirmed that customers faced issues with their banking services.
"We understand the root issues have been resolved, so we expect all our services to be back to normal soon," Lloyds said in a statement on Tuesday afternoon.
Internet service tracker Downdetector indicated that hundreds of reports had been made of problems affecting business in the UK, including the property website Rightmove, delivery service DPD and the Royal Mail postal service.
HSBC said its customers experienced "difficulties accessing our services", adding that it would "monitor the situation, which is also affecting other organisations".
A Revolut spokesperson said the bank was "working to fix the issue since it was identified" and offered its apologies "to anyone affected and for any inconvenience caused".
"We can confirm that all our customers' money and data are safe," the spokesperson added in a statement.
Reliance On Hyperscalers
Google said it would publish a full incident report in the coming days.
The outage has renewed concerns over the global reliance on cloud providers, which offer businesses on-demand IT resources without heavy investment in expensive server farms.
Local providers have seen their share of the market shrink in recent years and been captured by foreign giants known as "hyperscalers".
A global outage at Amazon's cloud services last year disrupted many online services for video games, business and transport firms and made part of the internet inaccessible for several hours.
Only three major hyperscalers -- Google Cloud, Microsoft Azure and Amazon Web Services -- have the infrastructure to handle vast amounts of data needed by businesses at scale in the UK, said University of Surrey cybersecurity professor Alan Woodward.
These centres remain "susceptible to localised infrastructure failures", which can have significant knock-on effects when so many businesses depend on just a handful of providers, he added.
He said the problem is "intensifying with the AI boom" as demand for hyperscalers rises, meaning "we are becoming more reliant on these few massive entities".
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)