The boom in online video has started to reduce the hours people spend watching television, a survey said on Monday.

The ICM poll of 2,070 people for the BBC found that some 43 percent of Britons who watch video from the Internet or on a mobile device at least once a week said they watched less traditional TV as a result.

Three quarters of users said they now watched more TV online or on mobiles than they did a year ago.

Online video viewers are still a minority though, with just 9 percent saying they go online regularly to watch clips.

Online and mobile video is far more popular among the young, with 28 percent of those aged 16-24 saying they watched more than once each week. That figure fell to just 4 percent among over 45s.

The success of sites such as YouTube has boosted access to videos for those who want easy ways to find, watch and share them over the Internet.

Unlike in the United States, where hit TV shows are routinely available from networks' Web sites and services like Apple's downloading store iTunes, Britain is still in the early stages of an online viewing boom.

But the BBC, ITV and Channel 4 are planning to offer most of their shows on demand on the Internet from the end of this year or the start of 2007.