O2 has responded to claims that it is throttling customers' speeds during peak usage times.
A recent article in the Register suggested that the frustrating internet experiences suffered by customers of both O2 and Be Broadband could be linked to the use of bandwidth throttling-related equipment.
While admitting that slow speeds had been experienced, an O2 spokeswoman said that the problem was a result of network congestion.
"We do not throttle speeds on our network," she told the technology news provider.
Continuing: "We are aware that some parts of our network are experiencing congestion at peak times. We are monitoring this closely and are investing heavily to increase the capacity in these areas."
A poll on an O2 users' forum found that 88 per cent of subscribers saw a "dramatic" speed decrease during evening hours.