Ladbrokes chief Chris Bell has come under fire from many areas of the racing industry after his claim that at least one race a day is fixed.
Bell told the BBC's 'The Money Programme' that at least one race a day was "corrupted by the availability of laying horses to lose on betting exchanges".
But the Jockey Club, the National Trainers' Federation and several pundits have all questioned his claims.
Several believe that racing's reputation is being caught in the crossfire between traditional bookmakers and betting exchanges.
The Jockey Club's executive director, Christopher Foster, dismissed Bell's comment, saying: "We know of no basis on which he could make such a claim.
"If Ladbrokes had any evidence of a pattern of so-called 'fixed races', they should have shared it with the Jockey Club under the Memorandum of Understanding - they have not done so."
Betting exchanges - where punters bet against each other and can bet on horses both to win and lose - have revolutionised the betting industry over the last couple of years.
Traditional bookmakers, including Ladbrokes, who are Britain's biggest bookies, want to see more legislation brought in to govern exchanges, which have cornered an increasing segment of the betting turnover market.
They have a powerful ally in the British Horseracing Board, who have called for a licensing system for those who lay horses on exchanges.
The National Trainers' Federation echoed the Jockey Club's caution about Bell's claim.
In a statement, the organisation also questioned his motives for airing the issue.
"Why would bookmakers seek to undermine the reputation of racing in such a
dramatic way? It is suggested that their strategy is related to their turf war
with betting exchanges," the statement said.
"If so, it is a mighty dangerous game to be playing with the reputation of a
large industry on which thousands of honest, hard-working people depend for a
Bell's comment is the latest in a series of allegations of corruption which have dogged the sport in recent months.
The Jockey Club is currently investigating several cases where alleged fixing has taken place.
It has also said it will conduct an inquiry into race-fixing accusations made by the News of the World against champion Flat jockey Kieren Fallon, allegations that the rider strongly denies.
The Money Programme: BBC Two, Wednesday 2 June, 1930 BST