Confectionery giant Cadbury's is to end its £10m-a-year sponsorship of ITV soap Coronation Street.
Coronation Street has one of TV's largest audiences
Cadbury's, which has sponsored the show for 10 years, said it wanted to look at new opportunities for its brand.
The end of the sponsorship, the most lucrative in terrestrial television, comes as a further blow to ITV which is struggling with its future direction.
The broadcaster has been searching for a new chief executive for months and is facing a potential bid from rival NTL.
Cadbury's latest two-year deal with Coronation Street expires at the end of 2007.
The company said it had agreed with ITV that if the broadcaster found a replacement sponsor before then, it would end its involvement earlier.
Cadbury's - whose adverts appear at the start and end of each episode of the soap - said that it had taken the decision to end the deal after refocusing its marketing strategy.
"Nothing lasts for ever," a Cadbury's spokesman said.
"Ten years is an awful long time for a sponsorship deal. Right now, we felt it didn't meet the needs of our marketing strategy."
The deal was seen as a landmark development in television sponsorship when it was signed in 1996.
Coronation Street regularly attracts more than 10 million viewers, making it one of the most-watched programmes on television and an extremely lucrative shop window for advertisers.