UKTV, the rejected high bidder for Channel 5, is poised to petition the High Court for a review of the controversial award.
The move, which could be announced on Monday or Tuesday, would put additional pressure on the Independent Television Commission, which awarded the10- year licence to a consortium led by the media companies Pearson and MAI.
The consortium, backed by CanWest, the Canadian broadcaster, and SelecTV, the independent production company, was said last night to be taking final advice from its lawyers, Clifford Chance.
Virgin TV, another rival bidder for the licence, was granted leave last week to have the decision reviewed by the High Court, during hearings scheduled for January. It is believed that Virgin's success in the courts emboldened UKTV to reconsider an earlier decision not to proceed with legal action.
A UKTV spokesman declined to comment, but sources close to the company said "fresh information" arising from the Virgin TV legal challenge had weighed heavily in their deliberations.
UKTV bid pounds 36m for the licence, but was rejected on quality grounds. Virgin TV and Pearson/MAI bid an identical pounds 22,002,000, while New Century Television, grouping BSkyB, Granada and others, bid a low pounds 2m. Only Pearson/MAI and New Century passed the ITC's quality threshold, and the licence was awarded to the higher of the two qualifying bids.