A Victorian farmer trapped in a hay baler for up to 36 hours had to be resuscitated at the scene before he could be transferred to hospital.

Emergency crews on Tuesday evening worked for almost three hours at the Mount Duneed property to free the critically injured man who’d become trapped on Monday.

“He was trapped in the hay baler for, we think, up to 36 hours,” Ambulance Victoria chief executive Tony Walker told 3AW on Wednesday.

“His heart had stopped when he was taken out of the machinery but we actively resuscitated and he was then able to be transported to hospital.”

Mr Walker said the rescue at the man’s property near Geelong was “amazing”.

“It was quite a difficult extraction with regards to the machinery that was involved,” he said.

It’s understood the farmer, aged in his 60s, was found by neighbours on Tuesday evening with emergency services called at 6.45pm.

It then took paramedics and CFA and SES crews almost three hours to free him.

“It obviously took some time because he was half in and half out of the hay baler,” a CFA spokeswoman told AAP.

“It was quite a delicate procedure to get him out.”

The injured farmer was initially taken to Geelong hospital before being flown by air ambulance to the Royal Melbourne Hospital where he remains in a critical condition.

WorkSafe Victoria is investigating.

-AAP