The clerk of the Mid Antrim 150 course said an oil spill which led to the cancellation of the race was "strategically placed".
Jack Agnew arrived on Saturday morning to find much of the course at Clough had been covered and a major clean-up operation ensued.
A mixture of oil and diesel was found on the circuit.
The event was cancelled at 12:30 BST and the police were informed.
Mr Agnew said he believed it was "deliberate because of the position it was put on the road - on the very fast bend, on the racing line and the breaking line".
"I believe that whoever did it knew what they were doing," he said.
Mr Agnew said "the fact that it was done during the night" also heightened suspicion.
"Police said the course was fine at 03.00 BST on Saturday but it was done by 05:00 BST", he added.
It is the second year the race has been affected by oil, although last year the damage was not as severe.
"This confirms that last year was probably deliberate as well," Mr Agnew said.
He said police were investigating and were examining CCTV footage.
Ryan Farquhar who was due to compete at the race said he "couldn't believe the amount of oil poured on the circuit".
"To me, the persons who put the oil down knew exactly where to put it to cause maximum disruption," he said.