Richmond's Sydney Stack has allegedly breached COVID-19 rules for a second time and is under Western Australian custody.

Stack returned to WA on compassionate grounds last Thursday and was issued to self-quarantine at home for two weeks.

But according to WA Today, Stack breached self-quarantine by going out in a party hotspot in Northbridge on Saturday night.

The 20-year-old was refused bail and will appear in a Perth Magistrates Court on Sunday.

This is the second COVID-19 breach by Stack who was suspended for 10 matches and fined $100,000 for breaching AFL COVID-19 protocols with teammate Callum Coleman-Jones in September.