Cobram Crime Investigation Unit detectives are investigating after more than 150 sheep were stolen from a property in Tungamah last month, Victoria Police say.
Investigators have been told 181 Suffolk/Merino cross lambs were discovered missing from the Lawrence Road property sometime between September and 20 December 2018.
The sheep, which were part of a larger flock, had been in the vicinity of Youarang, Walden and School roads.
They had been sheared on 22 September before being fenced in paddocks, however it was determined some were missing after they were counted on 20 December.
It was initially thought they may have escaped from the paddocks but police believe they were deliberately taken from the property by unknown offenders.
Police have released an image of some of the lambs in the flock in the hope someone may have information.
The livestock all had orange ear tags before being taken.
Anyone with information on the theft or the whereabouts of the sheep is urged to contact Crime Stoppers.