Thousands of Australians have gathered for the largest memorial service in Melbourne to mark a national day of mourning for victims of the country's worst wildfire disaster that has left at least 200 people dead.

The ceremony began on Sunday with bell rings at an arena in Melbourne, the main city of the disaster-hit state of Victoria.

Kevin Rudd, the Australian prime minister and Princess Anne, representing Queen Elizabeth, led the mourners.

Hundreds of survivors were brought on busses from the stricken region into Melbourne.

Other survivors living in tents or with friends since they lost their homes came together in parks and public areas to watch the ceremony and grieve.

The 90-minute ceremony was being broadcast across Australia, and smaller ceremonies were being held elsewhere in the country.

Worst wildfire

Police have said 209 people were killed, and more than 1,800 farms and homes were destroyed in the fires that swept across Victoria earlier this month, Australia's worst natural disaster in more than a century.

John Brumby, Victoria state's premier, said he hoped the ceremonies would "provide some healing".

"These fires have united us all in grief. They have united us all in our response, and they unite us all in the task of rebuilding. Because we will rebuild," Brumby said at the ceremony.

"This is something that has affected our state's psyche, the nation's psyche more than anything in my lifetime," he told Sky News television earlier.

Several fires were still burning in Victoria, with forecasts of more hot weather on Monday.

Jennifer Coate, Victoria's coroner, banned clear-up operations in several areas this weekend after new human remains were found.