Australia will observe a national day of mourning as a mark of respect to citizens killed in the Ukraine Malaysia Airlines crash.

Twenty-eight Australians are confirmed dead after the demise of flight MH17 on Friday, with authorities warning that number could rise.

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 In response to the “horrific” event, Prime Minister Tony Abbott has ordered that the national flag be flown at half-mast at all Australian government establishments on Saturday.

A national day of mourning will coincide with a national commemorative service at a later date “when the families of those who have lost their lives have had time to comprehend this horrific event”, he said.

Mr Abbott and Governor-General Peter Cosgrove will attend a service at St Mary’s Cathedral in Sydney on Sunday “as we stand together as a nation at this difficult time”.

Some 300 people were on board the plane when it was shot down.