Euro RSCG is believed to have triumphed in the three-way pitch against Leo Burnett and the incumbent, which was called earlier this month. The agency fielded a pitch team which was led by Mark Wnek, the joint chairman, and Adam Leigh, the managing director.
The loss will be a massive blow to O&M, as the account is thought to be worth about £1 million in income to the agency and comprises all aspects of the Argos creative account.
The pitch was overseen by Paul Geddes, the Argos marketing director, and Helen Page, the head of brand marketing. The pitch has involved creative presentations from all three agencies go through several stages of research over the past month.
Page joined the marketing team at Argos from Abbey National earlier this year. She was the bank's head of national communications.
Last October, she oversaw the reappointment of Euro RSCG to Abbey National's £14 million above-the-line account after a competitive pitch involving agencies including O&M.
The pitch initially centred on the launch of Argos' next catalogue, but has subsequently been extended to include the entire account. The company prints 43 million catalogues a year for its core home delivery business.
O&M's creative work for Argos has helped the retailer's annual sales top £2 billion. The catalogue store has achieved great success on the high street, with sales up by 14 per cent during the crucial Christmas period in 2001.
Previous Argos advertising activity has featured the model Melinda Messenger and used the strapline: "Brighter shopping, brighter prices." More recent advertising has used a sunflower as the brand's icon, accompanied by the song Sunshine On A Rainy Day by Zoe.
O&M's sister agency in the WPP Group, MindShare, handles Argos' media account, which is not thought to be affected by the review.
Argos has been part of the Great Universal Stores retail group since 1998. It provides the bulk of the group's sales and 36 per cent of its profits.
It currently has 473 stores in the UK and 15 in the Republic of Ireland but has announced plans to expand its presence on the UK high street.
An Argos spokeswoman denied that a decision on the creative account had been taken as Campaign went to press, while no-one at Euro RSCG was available for comment on the story.