At The Races insisted "no material impact on ATR's profitability is expected" after it was announced Ascot is to switch broadcaster to Racing UK from the start of the 2014 Royal meeting.
Racecourse Media Group-owned Racing UK are responsible for the majority of Britain's major racecourses, including Cheltenham and Newmarket, and Ascot has decided to follow suit.
At The Races, which has exclusive rights to racing in Ireland, lost Exeter, Kelso and Perth to its rivals earlier this year and Folkestone and Hereford will also be missing from next year's line-up as both racecourses will shortly close down.
Ascot officially joins the Racecourse Media Group on June 12, 2014.
A statement posted on the At The Races website read: "At The Races is naturally disappointed that Ascot has chosen not to continue its relationship with the company from June 2014, a relationship which goes back to 2004 and which has at all times been conducted on the best of terms.
"At The Races enjoyed a record year in 2011 and is on track to surpass those achievements in 2012. As a shareholder in the company, as well as a media rights licensor, Ascot is a major beneficiary of this success and, factoring in the company's growth plans going forward, looked set to reap significant further financial returns longer term.
"No material impact on ATR's profitability is expected as a result of this decision as the company's revenue lines continue to grow and diversify. Ascot's rights accounted for 4% of total ATR revenues in 2011."
Ascot's chief executive Charles Barnett said: "After careful consideration we have decided to extend our relationship with RMG, with whom we recently negotiated the exclusive terrestrial television contract with Channel 4.
"We have also partnered with the RMG courses since 2007 in the provision of our pictures to betting shops through Turf TV.
"Enabling a large percentage of the best of British racing to be promoted by one entity and showcased through one satellite broadcaster mirrors the thinking behind the Channel 4 deal, and it should benefit initiatives like the Qipco British Champions Series."
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