The Turnbull government has sent a stern warning to Fremantle council to move its Australia Day celebrations back to January 26 or be banned from hosting citizenship celebrations.

The council caused outrage in August when canned its traditional Australia Day fireworks and then angered both the Barnett and Turnbull governments when it announced a "culturally-inclusive alternative event" on January 28 instead.

Fremantle council's decision also caused a storm on social media, with thousands of people venting their anger at the city on the WAtoday Facebook page.

Now Assistant Minister for Immigration Alex Hawke has written to the City of Fremantle, threatening to stop it holding any citizenship ceremonies unless celebrations were moved back to January 26.