Skype customers around the world have been locked out of the popular VoIP service this morning because of what the company describes as "peer-to-peer network issues".

The service has been down all morning UK time, with connectivity returning for irregular short periods and then dropping off, according to users.

A Skype company blog carried an apology today for the connectivity issues.

"Due to peer-to-peer network issues there are problems with Skype login. This issue is being investigated. We will give new updates when the issue has been resolved. We apologise for any inconvenience," said the entry.

Since going to press Skype has issued the following statement: "UPDATED: Some of you may be having problems logging in to Skype. Our engineering team has determined that it's a software issue and hopes to have this resolved quickly.

"Meanwhile, you can simply leave your Skype client running and as soon as the issue is resolved, you will be logged in. We apologize for the inconvenience."