Australia's most decorated canine war hero, who went missing in Afghanistan for over a year, has died after a short battle with brain cancer.

The bomb-sniffing dog was awarded the War Dog Operational Medal and the RSPCA's Purple Cross, its highest award for animal bravery.

Sarbi, Australia's most decorated military dog, has died. Credit:Jeffrey Chan

The 12-year-old Labrador-Newfoundland cross was only the second animal to win the Purple Cross for wartime service, following Murphy, one of John Simpson Kirkpatrick's famous Gallipoli donkeys.

Her handler, David Simpson, wrote on Facebook that Sarbi had suffered a number of seizures in recent weeks and that a scan last week had uncovered a brain tumour.