The marque, which is owned by troubled car giant General Motors (GM), handed the advertising briefs for its Astra and Corsa models to Delaney Lund Knox Warren at the end of last month. Both were scheduled to run in March, but the Astra work has now been delayed.
It is understood the work was dropped in favour of the Corsa activity because the Astra is more established and less in need of ad support.
The decision is believed to have been made due to GM placing pressure on marketing budgets. Last month the company announced global losses of £4.8bn for 2005, which it described as one of the most difficult years in its history.
GM has been pursuing cost cuts across its group.
Following the appointment of Alain Visser as Opel's executive director of marketing in 2004, the group adopted a practice of holding pitches for individual briefs among its roster agencies. The work is then rolled out across Europe by McCann-Erickson.
Vauxhall UK would not comment on future advertising plans for the Astra.