Virgin TV Anywhere follows in the footsteps of BSkyB's rival Sky Go service
Virgin Media has launched an internet TV service that streams programmes to computers, tablets and smartphones.
The TV Anywhere service is available to UK customers but they will need to rent a Tivo set-top box from the company and upgrade if on a basic package.
It signals a challenge to BSkyB's rapidly growing Sky Go service.
It may also deter users from cancelling subscriptions to make use of cheaper catch-up TV alternatives and media libraries such as Lovefilm and Netflix.
At launch, streaming shows via Virgin TV Anywhere will only be possible with a wi-fi or broadband connection.
Virgin said it had not paid for the separate rights necessary to offer it over 3G or 4G phone networks - although other functions such as setting a Tivo recording from a remote location would be possible via cellular connections.
By contrast Sky Go does stream media over 3G and 4G.
The new Virgin product offers the ability to view live broadcasts from up to 45 channels including several of Sky's premium sports and movie options if the customer has an existing subscription.
In addition catch-up content is available from a smaller number of channels, although this is limited to PCs at this point.
Virgin said that two-thirds of its customers already made use of the catch-up services it offered to TV sets.
The program is based on Tivo's own Buddy program released about 18 months ago in the US.
PCs will access the facility over the internet and there is an app for iPhones and iPads.
Virgin said it was also working on a version for Android, but would not release it before 2013 because of the extra effort needed to ensure it worked across the platform's wider range of devices.
In addition Virgin said it was looking to release an app for Windows Phone 8 and other devices, but could offer no guarantee at this time.
Virgin will be hoping to emulate the quick take-up of the rival Sky Go service.
Launched in July 2011 it has proven particularly popular with sports fans with golf's recent Ryder Cup providing its biggest ever audience.
"Sky has said that the service now has 2.8 million users - given that it requires a certain amount of technical ability to use it that's a pretty impressive figure out of its 10.6 million user-base," James Barford from Enders Analysis told the BBC.
"The Sky evidence indicates that people really do use a service like this, so Virgin is doing it both to match or exceed the functionality of Sky but also as a defence against the YouView service which offers catch-up programming but only via a television set."