Aust must recognise genocide: Robertson

Internationally renowned human rights lawyer Geoffrey Robertson has called on the Australian government to recognise the slaughter of hundreds of thousands of Armenians in modern-day Turkey 100 years ago as genocide.

As Australians prepared to commemorate the centenary of the Gallipoli landings, more than 2000 members and supporters of the Australian Armenian community gathered at Sydney Town Hall to remember the victims of mass killings that began in the Ottoman Empire on April 24, 1915.

Turkey has consistently denied the deaths of up to 1.5 million Armenians amounted to genocide.

"Isn't it ironic that here we are, 100 years after (Gallipoli), celebrating the courage of young Australians in facing Turkish bullets, and we have a government that lacks the courage to stand up to Turkey?" Mr Robertson said in his keynote address.

"I can't refute what is obvious to every honest scholar, that what went on in 1915 was genocide."

Mr Robertson said the key difference between the original Anzacs - including his great-uncle Bill Robertson, who was among the first to die in sniper fire at Anzac Cove - and the Armenians, who were killed only hours earlier and in the years that followed, was that the diggers had volunteered to fight.

"They were victims of a crime," he said of the Armenians.

"They deserve not just mourning, they deserve a particular concern and commemoration. Not just a remembrance, but a demand."

Human Rights Commissioner Tim Wilson and Treasurer Joe Hockey were among the high-profile attendees at Friday night's event.