A national memorial service for victims of the MH17 disaster will be held in Melbourne on Aug 7, Prime Minister Tony Abbott has announced.

The multi-faith service will be held at St Patrick's Cathedral.

"I hope many members of the public will attend to support the families of the victims," the Australian Associated Press (AAP) cites Abbott as telling Fairfax Radio Thursday.

Nearly 300 people, including 37 Australian citizens and permanent residents, died when a Malaysia Airlines plane was shot down over eastern Ukraine on July 17.

The service was being held in Melbourne because 16 of the victims, including three Malaysians, came from Victoria, Abbott said.

On the day of the service, flags on all Australian government buildings, in Australia and overseas, will be flown at half-mast. Arrangements have been made for an outside broadcast in anticipation of a large crowd.