Thieves branded heartless and selfish stole 50 posts from the Pomborneit Recreation Reserve, which was significantly damaged during the February 7 blaze.

The treated pine posts were found in bushes near the entrance of Lake Bullen Merri's South Beach on Wednesday night.

Pomborneit Recreation Reserve treasurer Terry Place was sickened by the theft. He believed a guilty conscience forced the offenders to dump the items.

"It looks like they realised what they were doing and got rid of the posts before anyone found out," Mr Place said.

"It was a pretty low act."

The recreation reserve faces a massive rebuild effort. It is estimated the fire caused $100,000 damage.

While no buildings were lost, the blaze destroyed a significant part of the cricket ground and melted external plumbing on the reserve's clubrooms.

Ground committee members discovered the theft early Monday. They were set to rebuild the reserve's boundary fence to allow farmers to use adjoining pasture.

Mr Place said other posts were sourced from neighbouring landholders to complete the job.

"Now that we have these posts back we can repay the people who helped us out with the replacement posts.

"They will definitely be put to good use."

Constable Lauren Conte, of Camperdown police, said the theft was still being investigated.

She urged people with information to contact Camperdown Police or Crime Stoppers on 1800 333 000.