Horse racing: Whitelocks' horses embroiled in drug scandal

One of the year's biggest days of racing, the Harness Jewels in Cambridge, has been rocked by a drugs controversy. 

Betting on six races has been suspended, while ten horses are being tested.

It was revealed they had been in contact with workers who smoked drugs during the trip north from Christchurch.

Three of those horses are owned by Braeden and Caroline Whitelock, father and mother of All Blacks, Sam and Luke Whitelock.

Mr Whitelock told Newshub they aren't sweating on the outcome of the testing, and were confident their horses would be cleared to race on Saturday.

"From my perspective, it's pretty much precautionary and going through the protocols," said Whitelock. "We look forward to a positive result."

Nine of the horses are trained by the glamour partnership of Mark Purdon and Natalie Rasmussen, who alerted authorities.

"We would hope that four o'clock on Friday all the horses will be cleared and it will be all fine to race," Racing Integirty Unit General Manager Mike Godber told Newshub.

"There is a chance that they may not be the case, and because of that we've had to put in the suspension of betting."

Any horses returning positive tests on Friday will be scratched from Saturday's racing.