Virgin Media has put a traffic management policy in place which could throttle its broadband customers' download speeds by up to half. Update - See also: Virgin Media says throttling is nothing to worry about.

The updated policy was brought into place yesterday and will throttle both download and upload speeds if users go beyond a usage allowance. If the cap is broken then a speed reduction will take place for five hours.

Usage will be monitored daily between 10am and 3pm, then 4pm to 9pm. However, customers will have to have to use between 3.5GB and 20GB of data, depending on their package, during these times to trigger the throttle. This is the first time subscribers to 50Mb and 100Mb have had traffic management.

Virgin Media said: "The policy has been designed to reduce the impact of the top 5% of heaviest users on a daily basis, reducing the detrimental affect of these customers’ extreme usage on network performance and the service other customers receive."

For example, subscribers to Virgin Media's 30Mb package will see a five hour speed reduction of 50 percent if they exceed 7GB of usage between 10am and 3pm. The usage cap is reduced to 3.5GB between 4pm and 9pm. You can see exactly how it will affect you on this document.

Upload speeds will also see a hit of either 65 percent or 75 percent depending on the broadband package. Once again, the duration of the throttle is five hours and will occur if users go over caps starting at 3GB.

Virgin Media already angered its customers recently by introducing a price hike at the same time as doubling its download speeds. This new policy effectively cancels out the free speed upgrade but only if the usage allowance is broken.

"Virgin Media’s traffic management policy is designed to ensure the vast majority of customers get the high quality of service they expect from Virgin Media’s fibre optic broadband without being negatively affected by extremely heavy users using more than their fair share at the busiest times." added the firm.