Millions of O2 customers have been left without data services for more than six hours.

Customers with O2 as well as Tesco Mobile and GiffGaff, which the company also offers services to, have all been left without 2G, 3G and 4G networks since early this morning because of a global software issues from a third party supplier.

O2, in statement, said: "We’re aware that our customers are unable to use data this morning. One of our third party suppliers has identified a global software issue in their system which has impacted us.

"We believe other mobile operators around the world are also affected. Our technical teams are working with their teams to ensure this is fixed as quickly as possible.

"As a result of this incident, we are experiencing a high demand on our network which means some customers may have issues making and receiving voice calls.

"We’d encourage our customers to use Wifi wherever they can and we apologise for the inconvenience caused.”

Wireless networks are unaffected by this issues.

O2 have been keeping customers up to date through online avenues today.

The latest post on Twitter said: "Outage update: Our teams are working closely with one of our third party suppliers who has identified an issue in their system which has impacted mobile services globally.

"This is our top priority and we are really sorry. Get updates here:"