LONDON — British mobile phone operator O2 said Friday that its 4G network was restored after a glitch with software made by Sweden's Ericsson left tens of millions without service.

"I want to let our customers know how sorry I am for the impact our network data issue has had on them, and reassure them that our teams, together with Ericsson, are doing everything we can," Mark Evans, CEO of Telefonica (O2) UK, said.

The outage wreaked havoc across Britain on Thursday, with millions of drivers unable to use navigation apps and customers not having the option to use their phones to make in-store purchases.

In London, electronic boards announcing the arrival times of buses went dark while Uber drivers complained of being unable to pick up customers. Telefonica, the Spanish owner of O2, said the outage was noticed in London at around 5:00 a.m. on Thursday.

It blamed the issue on "certain nodes in the core network resulting in network disturbances for a limited number of customers across the world, including in the UK".

O2, which has 25 million customers in Britain, also has another seven million people whose mobile providers "piggyback" its network.

Japan's SoftBank said its customers had faced a near five-hour outage "caused by Ericsson-made software errors related to its packet switches, covering our customers nationwide".

The Japanese company also cited an Ericsson report that indicated that telecom carriers in 11 countries were hit. Ericsson's chief executive Borje Ekholm issued an apology in the late afternoon.

"The faulty software that has caused these issues is being decommissioned and we apologize not only to our customers but also to their customers," Ekholm said.

"We work hard to ensure that our customers can limit the impact and restore their services as soon as possible." — AFP