Anzac Day marks the ill-fated World War I landing of Australia and New Zealand Army Corps troops at Gallipoli, in what is now Turkey, in 1915.

Facing dug-in German-backed Ottoman forces, more than 10,000 Australian and New Zealand servicemen were killed in the Allied expedition.

This year marks the 110th anniversary of the landing.

Anzac Day now honours Australians and New Zealanders who have served in all wars, conflicts and peacekeeping operations.

"We who are gathered here, think of those who went out to the battlefields of all wars, but did not return," Australian Prime Minister Anthony Albanese, who attended a service in Canberra, said.

"We feel them still near us in spirit. We wish to be worthy of their great sacrifice."

New Zealand's Prime Minister Christopher Luxon will attend an Anzac service in Gallipoli.

Britain's King Charles III thanked the thousands of Anzac troops for their "selfless service in those most difficult and dangerous times".

The annual commemoration comes in the run-up to a May 3 election in Australia, where the most pressing issues for both parties are the cost of living, managing the energy transition and balancing relations with the United States.

The left-leaning government is leading the opposition in opinion polls.