Broadcast transmission company Crown Castle, which owns a stake in Freeview along with the BBC and BSkyB, revealed it was adding the channel after improvement to the technology that broadcasts the service.
The new channel opportunity will raise considerable interest among UK and US broadcasters, with Channel 4 likely to pitch entertainment channel E4 to Castle.
Disney, which launched ABC1 featuring US sitcoms like '8 Simple Rules for Dating My Teenage Daughter' and 'Home Improvement' on Freeview last year, is likely to put forward the channel. It will then be able to run for 18 hours as opposed to the limited 6am-6pm time slot it currently has on Freeview.
Other contenders could include ITV, which is planning to launch ITV4 later this year, and Five, which is planning a children's channel from its popular Milkshake programming strand.
A Crown Castle spokesman said: "Castle has issued a request for proposal to interested parties for additional broadcast capacity, although we can't discuss potential buyers at this stage."
The new channel slot is due to debut on April 1 2005 and the eventual buyer will be tied into an initial 12-month contract.
The news comes as record Christmas sales have increased the number of Freeview households in the UK to 5m, compared with almost 4m at the end of September.
Digital take-up is expected to soar as Sky's FreeSat and Freeview go head-to-head for customers.
Already the price for Freeview set-top boxes has dropped dramatically and they can now be bought for around £50. The BBC's recent "boxer" on-air digital campaign promoted all routes to the BBC's six extra BBC channels and services.
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