Archbishop Glenn Davies has warned of the seriousness of the situation facing Sydney Diocese in coming months, saying further advice will be forthcoming from the Diocese's COVID-19 Task Force.

"This is a health crisis of unprecedented proportions. No one who has read any of the statements of health experts and government officials or has simply looked at the internet in recent days could underestimate the seriousness of this situation," Dr Davies wrote to church leaders.

"Our response should be of Christian faith, fervent prayer and godly love."

The Archbishop said "Our health practices are an important outworking of loving our neighbour and especially our brothers and sisters in the household of faith. Yet we must still find ways, outside of our normal structures, to love, support and fellowship with our communities around God's word."

Bishop Gary Koo, the Bishop of Western Sydney who formerly practised as a doctor, is chairing the COVID-19 Task Force for the diocese.

"Gary's medical training is invaluable in this crisis and his addition to the episcopal team at this time is clearly providential," Dr Davies said. "His main task will be to assess, with others, the medical advice from NSW Health as it applies to our churches."

Australia’s leading medical officers will meet today (Tuesday) and Dr Davies said a further update on church gatherings will be issued within 24 hours.

"There will be difficult times ahead which will test our commitment to the Lord and to his people. We shall face criticism from those who consider us alarmist, and from those who consider us irresponsible. However, what should characterise our actions are faithfulness to God and love of all people. May God empower us to such action which is pleasing in his sight and brings honour to his name."