Rallying cost talks stall with Natural Resources Wales
Concerns have been raised about rallying in Wales' forests as the sport's governing body said new costs sought by Natural Resources Wales (NRW) would be "unworkable".
The Motor Sports Association (MSA) has agreed deals in England and Scotland but talks are continuing in Wales.
NRW said it had to recover its costs.
Former British rallying champion Gwyndaf Evans said he was concerned racing could become "prohibitively expensive" in Wales.
"If these increases happen... there's a danger that rallying may have to stop in Wales," he said.
"And that would be a tragic loss to all the competitors but also all the suppliers throughout the sport and to tourism in Wales."
The nation hosts several competitions with the Wales Rally GB, the final round of the FIA World Rally Championship (WRC), the most high profile with stages in Powys, Gwynedd and Denbighshire last year.
Mr Evans explained that a national rally stage in Wales costs about £500 to enter, with organisers needing about 80 competitors to break even.
He said a forestry fee increase would push up entry prices and could mean fewer competitors, making events unviable.
MSA boss Rob Jones said: "Unfortunately, we have yet to reach agreement with NRW, which is currently seeking an increase that would be unworkable for rallying in Wales and thereby detrimental to the country's hugely successful motor sport industry and also to the many local communities that benefit from the sport.
"However, we continue to work hard on behalf of the sport in Wales and with discussions continuing we remain confident of reaching agreement with NRW as soon as possible."
A rate of up to £688 per mile has been set in England and Scotland for some rallies.
NRW head of enterprise David Edwell said: "We have a long and proud history of staging rallying events in Welsh forests and are working closely with the Motor Sports Association to reach an agreement that will allow this to continue.
"It is, however, important that the costs we incur in preparing the forests for these events and repairing the roads afterwards are recovered so we can deliver the wide range of other services these areas provide to the people of Wales."
Last year's fees are in place in Wales until the end of May.