Bookmakers at the Cheltenham Festival, which is due to begin tomorrow, have been urged to beware of gamblers trying to launder money stolen in the £26.5 million Northern Bank robbery in Belfast.
Felix McKenna, chief of Dublin's Criminal Assets Bureau, said: "What better place to launder dirty money than the races?
"Cheltenham is an ideal venue to put £500 or £1,000 in cash on a horse to clean it up.
"They will be in there in their dozens. I would like to warn the bookies that there will be Northern Irishmen at Cheltenham bringing large amounts of money and putting it down as bets."
While English sterling, rather than Northern Bank notes, represents a significant part of the sum stolen, it is thought the bank is unable to supply an accurate breakdown of the currency's composition.
Mr McKenna said: "The best place to launder English money is where it is the common currency."
Banks and other financial institutions usually check only those depositing large sums of cash, usually more than £10,000, in a single slab.
But while betting companies must report large or suspicious deposits, smaller sums in larger numbers give a launderer an efficient way of disposing of suspicious notes.
Although the money spent on a race runs the risk of a loss, the criminals could follow the example of one convicted Irish fraudster who spent vast sums in bets over a short period of time on every horse in a race.
This allowed him to make a predictable return on the investment, although with a loss.