Virgin Media has blamed coders of the popular Xbox Live game Call of Duty: Black Ops for slow connection issues that are hampering its service.

"We're aware some of our customers are experiencing issues whilst playing Call of Duty: Black Ops on Xbox Live. Xbox Live traffic isn't managed by our systems so we've taken a close look at our service to see if there are any other problems, such as traffic routing, that could be contributing to these issues," a Virgin Media spokesman told The Register.

"Our investigation hasn't found any issues with our service so we have been attempting to contact the developers to try to understand further why customers are having problems."

But the telcos' customers don't altogether agree with that assessment, with some labelling Virgin Media as the UK's "worst gaming ISP".

Many have been complaining for months in VM forums about the lag issues, but the company's customers feel largely ignored.

"I've just had to quit multiplayer, lagging way too much and keep getting rubbish scores because I'm dead before I even see it on screen! SORT IT OUT!!!," reads a typical complaint from May this year.

Despite that, Virgin Media maintains that it has made repeated yet fruitless attempts to get in touch with Activision Blizzard Inc, which is the console game publisher behind titles that include Call of Duty: Black Ops .

"Unfortunately, despite numerous attempts at contact through a variety of channels, we are still waiting for feedback. As soon as we have any contact we will be working with them to resolve this issue as quickly as possible," the Virgin Media spokesman said.

To back up its protestations against Activision, Virgin Media pointed us to this video explaining the lag glitch.

However, Reg reader Paul claimed that he hadn't experienced the same problem with any other UK ISPs when playing the online game.

And it's not just Call of Duty that's hitting the buffers for VM customers.

"For the last two or three months now people have been unable to play any Xbox game without encountering issues. Basically because Virgin have a traffic management policy that borders on the absurd and all console gaming traffic is now P2P you can kiss goodbye playing on the Xbox no matter if you are on 30Mbit/s,50Mbit/s or 100Mbit/s connection," Paul told us.

"The general problem that occurs is that when you try and read/send a message it will take over 30 seconds to do so. When you try to start a private chat or Party chat the same will again happen and if you try to do too many of these at once you will be kicked off Xbox Live," he added.

Earlier this year a gamers' lobby group reported Activision to the UK's Office of Fair Trading.

Gamers' Voice, which was founded by Labour MP Tom Watson in 2009, claimed in January that the Call of Duty: Black Ops game failed to function as advertised. Gripes included sudden disconnections from multi-player sessions online.

The Reg asked Activision to comment on this story, but at time of writing it had not got back to us. ®