The South Australian government has cast doubt over the AFL's return to play timeline in a letter sent to AFL's Chief Executive Officer Gillon McLachlan, as published in The Australian.

The ruling, made by SA chief public health officer Professor Nicola Spurrier and the Commissioner of Police Grant Steven, means Adelaide and Port Adelaide players are not exempted from strict quarantine requirement.

There was a growing confidence within the AFL that South Australia government would relent on their border restrictions and give its AFL teams exemptions to help restart the season. That confidence has now been squashed with the letter.

"On public health advice, the committee has resolved that any economic and social benefits to be gained by allowing modification or exemptions to SA quarantine requirements for AFL players and staff were not outweighed by the public health risk," the letter said.

The ruling throws the fly-in-fly-out model out the window, with players and staff having to quarantine for 14 days once they cross the border into SA. It is looking likely that Adelaide and Port Adelaide will be joining West Coast and Fremantle in relocating to an Eastern seaboard hub in the hopes of getting the season restarted.

"We acknowledge that for the AFL to recommence fixtures on it preferred timeframe this may require players and staff to travel to an alternate location for the medium term," the letter said.

The letter has challenged the AFL's training plans by banning contact training until June 8.

The league had wanted all teams to be group training from next week. It seems unlikely unless SA and WA clubs immediately relocate.

West Coast Eagles are set to head to the Gold Coast to resume training.