O2 has apologised for a service outage which hit millions of its customers on Friday.

The mobile operator has said sorry after a technical problem with some network nodes left millions of O2 users without calls, text messages or data on their smartphones or 3G tablets. O2 said that around 10 percent of its 23 million customers were affected for three hours.

O2 said: "We are genuinely sorry that a number of customers had problems with their service on Friday afternoon and evening. The problem is now fixed and full service has been restored. We can assure all our customers that we are continually working to improve the consistency of service they get from our network."

Although the fault was fixed in the afternoon, the firm admitted that 'rush hour' traffic meant customers may have experienced intermittent performance. The outage may have also affected GiffGaff and Tesco Mobile users which use O2's network.

Unlike its outage which happened in July, O2 is not offering any compensation for customers affected by the outage.

Answering about whether it happened again, O2 said: "We operate to the highest industry standards and using leading industry infrastructure. We will continue to challenge and assess what further steps we and our infrastructure partners can take to further improve our network performance."