UP TO 10 jockeys face bans because they placed bets through third parties.

A $10,000 bet Damien Oliver put on a rival horse was placed by a professional punter, sources close to the jockey have said, as racing insiders say the practice is widespread.

In a development that could widen the betting scandal, it is understood as many as 10 jockeys face sanctions over their bets through third parties.

"Jockeys are always placing bets," said one well-known jockey who reeled off the names of several professional punters used to place clandestine bets.

"The funny thing is...jockeys are terrible tipsters. It's the trainers who are really in the know."

One punter is believed to have co-operated with authorities only after being threatened with a lengthy track ban.

Well-placed sources say he maintains a ledger that records bets of a number of top-flight jockeys.

Industry sources say as many as 10 high-profile jockeys could face sanctions as a result of inquiries under way, further damaging a sport still reeling over the Oliver affair.