A confrontation has developed between a number of agencies - thought to include ZenithOptimedia - over the terms and conditions of their airtime deals.
This follows the end of a two-week grace period in which media agencies were allowed to continue to use the terms and conditions of their 2003 deals for the first two weeks of January, until a new deal was negotiated for 2004.
During this time, the agencies were meant to let ITV know if they wanted to use the new Contract Rights Renewal procedure. This would have allowed them to fall back on last year's deal for the whole of 2004 if they could not agree modified terms.
Those agencies that historically gave ITV a disproportionately high share of their clients' advertising budgets - including ZenithOptimedia - are likely to have wanted to reduce their commitment to the channel in the light of audience changes or changing client portfolios and turned down CRR.
Chris Hayward, the TV director at ZenithOptimedia, played down the impasse.
He said: "I think that across the industry ITV is still in the process of negotiating deals. I doubt that there would be many deals completed as the account directors at ITV Sales were not in place until 15 December."
Sources claim that the dispute between MindShare and Sky Media has now been resolved. However, some disputes are ongoing with Unilever not thought to be advertising on the Sky channels.