Betfair has been told to '"cease and desist" operating on Hong Kong racing in a strongly worded letter from the Jockey Club.

The HKJC said it was caught by surprise when the betting exchange made the announcement last month it was to start operating on Hong Kong racing.

The club said there was no consultation between the two parties and given Betfair had made its intention public without any agreement, the HKJC was also going public with a response.

"The Club takes this matter seriously as it represents a serious integrity issue and an equally serious infringement of its intellectual property rights," HKJC secretary Philana Poon said in a letter to Betfair chief executive Tim Moore-Barton.

"In addition, creating the opportunity for people to back horses to lose is against what we all believe in."

"As a matter of principle and consistency, the Club considers that Betfair ought not be permitted to exploit overseas racing where there has been no approval from the relevant overseas racing authority.

"The Club demands that Betfair immediately cease and desist from: offering, in any capacity or form, wagering via its betting exchange platform (including in-play betting) on Hong Kong racing; promoting or otherwise advertising, in any manner, wagering via its betting exchange platform (including in-play betting) on Hong Kong racing.

"As noted above your announcement that Betfair would be offering wagering on Hong Kong racing was made without any prior notice to the Club. You made the announcement via Twitter and YouTube, and we were first made aware of it by the media. On a similar basis we are making this letter public via the media to place our concerns on the public record."

The club also expressed its concerns over Betfair's parent company Crown Resorts.

"The Club is also critically concerned about the context in which Betfair's move to commence wagering on Hong Kong racing has occurred. As you will be aware, in recent days, a series of serious allegations have been published in the Australian media (and internationally) regarding apparent historical failures by Crown Resorts to oversee and manage fundamental risks to entities controlled by it," the club said.

"The allegations include, but are not limited to, allegations that Crown Resorts or its agents, affiliates or subsidiaries engaged in money-laundering; breached gambling laws; and partnered with junket operators with links to drug traffickers, money launderers, human traffickers, and organised crime groups.

"Of particular note, on 8 August 2019, the New South Wales Government's Independent Liquor & Gaming Authority announced an inquiry into a proposed sale of shares in Crown Resorts.

"In its announcement, the L&G Authority acknowledged the recent media reports, and stated that such an inquiry was necessary having regard to the primary objectives of the Casino Control Act 1992 (NSW), which include ensuring that the "management and operation of a casino remain free from criminal influence or exploitation, that gaming in a casino is conducted honestly and controlling the potential of a casino to cause harm to the public interest and to individuals and families.

"Such an inquiry into your holding company's operations within the highly regulated casino industry manifestly raises concerns over the adequacy of corporate governance measures adopted throughout the Crown Resorts group.

"Betfair's approach of commencing operating on Hong Kong racing without having secured any authority from the Club to do this has done nothing to alleviate those concerns."