British broadcaster Channel 4 is intent on "vigorously defending" claims of ageism by John McCririck after the former pundit initiated legal proceedings against them, seeking damages totalling STG3 million ($A4.60 million).

McCririck was one of a number of faces dropped from the presenting team after Channel 4 awarded the production contract for its racing coverage to IMG Sports Media, ending its previous agreement with Highflyer.

McCririck was vocal in his criticism of the decision when it was announced last October and has decided to pursue Channel 4 and IMG Sports Media through the courts.

"We are grateful to John McCririck for his contribution towards the success of Channel 4 Racing over many years," a spokesperson for Channel 4 said.

"However, we reject the suggestion that discrimination on the basis of age played any part in the decision not to renew his freelance contract and we will be vigorously defending this claim."

In a statement issued to Press Association Sport, McCririck said both companies had been served with letters ahead of his legal action.

"After 29 years with Channel 4 Racing, on a rolling annual contract, I have been sacked without any consultation or cogent explanation. I am 72," he said.

"For loss of future earnings, unfair career damaging, public humiliation, stress and mental anguish, I will be seeking STG500,000.

"Ageism is illegal. For tens of thousands of employees it has become the feared scourge of our society.

"This litigation should prove to be a watershed.

"I am seeking a further exemplary, punitive STG2.5 million ($A3.84 million), part of which will be donated to charitable organisations helping to prevent negative prejudice in the workplace."

McCririck says he will drop the legal action if he is "fully" reinstated, receives an apology from Channel 4 and all his costs are met.

IMG Sports Media assumed production control on January 1, with former BBC racing presenter Clare Balding and Racing UK anchorman Nick Luck heading up the new team.