Industry figures believe high prices being achieved for both wool and meat are driving an escalation in large-scale theft of sheep across Victoria in recent months.

In the most recent incident, offenders broke into the Ballarat Livestock Selling Centre between 9pm on December 7 and 8am the next day, making off with 60 young breeding ewes.

The theft took place during Ballarat's annual ewe sale, where sheep were selling for up to $326 a head.

Ballarat Stock and Station Agents Association president James Haddrick said strong prices in the industry mean every sheep or lamb being stolen is worth more than $150 per head.

"It's a bit of a thing that is happening at the moment, they are being very brazen," he said.

"The thefts in Ballarat were out at the sales yard, they have actually been stolen straight out of the yard."

Mr Haddrick said the thieves were clearly not merely opportunists, but would have to be people who intimately understood the layout and operation of the yards.

He said stealing scores or hundreds of sheep would take specialist transport and a strong working knowledge of the stock.

"We have had a few stock thefts on properties as well, larger numbers up to 200 stolen from a property," he said.

"A little box trailer is not going to be able to do that."

Hundreds more sheep have been stolen in recent months in raids on at least half a dozen properties across the western district and north-central Victoria.

The thefts have the whole stock industry talking. Although proof is hard to come by, fingers are being pointed.

"There are some unsavoury people out there who have been guilty of stock theft before," Mr Haddrick said.

"But you can't have a crime scene and go and fingerprint somewhere that tens of thousands sheep have passed through."

Since being stung by the theft, the Ballarat sales yard has taken measures to increase surveillance and beef up security.

Mr Haddrick said the sheep rustlers will eventually come unstuck if everyone remains vigilant and reports anything out of the ordinary happening on properties and in sales yards.