Police say dead koalas and other frozen road kill may be used to disrupt the Australian leg of the Repco World Rally Championship in the Tweed Valley tomorrow.

Head of the Tweed-Byron police, Superintendent Michael Kenny, told local media protest groups rallying against the racing event would be watched closely after rumours began circulating about the use of dead animals, the lighting of fires and people laying across the track.

"Some of the bizarre things are that there is road kill been put in freezers that is going to be thrown on to the road during the event," Superintendent Kenny said yesterday.

"That's a rumour at best but I'm saying there are a lot of stories going around about this sort of madness that may or may not occur."

Protest groups No Rally and Kyogle-based 7th Generation oppose the rally on environmental grounds, claiming it will frighten off wildlife and disrupt the areas breeding season.