The prime minister will tell the crowd at an Anzac Day dawn service in Papua New Guinea that Australia "will never forget" the help the country's people provided to Australian soldiers during World War II.

Anthony Albanese is marking Anzac Day with the completion of a two-day, 16-kilometre journey along the Kokoda Track with PNG's Prime Minister James Marape, a visit the leaders have used to highlight their shared legacy of war in the context of a growing security relationship.

Mr Albanese will address hundreds of trekkers at an Anzac Day dawn service near the village of Isurava in the early hours on Thursday. The village is the site of an intense six-day period of fighting by Australian and Papuan infantry against Japanese soldiers trying to capture PNG's capital Port Moresby.

"We are gathered in a place that has known the most pitiless ferocity of battle, fought with bullet, bayonet, mortar, and the desperation of bare hands," Mr Albanese is expected to tell the crowd at the Isurava Memorial Site.

"It is also a place that has seen the unadorned strength of the Australian spirit.

"We feel the weight of history as we gather here along the Kokoda Track, this great artery of mud and suffering and perseverance that has come to occupy a place of singular power in Australia's shared memory."

Ninety-nine of the 625 Australians who were killed on the Kokoda Track died in the Battle of Isurava.

Mr Albanese will use the speech to highlight how the events of the war forged a powerful bond between Australians and the people of PNG.

"We thank every one of them who helped Australians in the face of retribution and sometimes unfathomable cruelty," he will say.

"The troops, the coast watchers and the shipping pilots.

"The villagers who risked their own lives to feed and guide and shelter Australians in desperate need. The stretcher bearers whose courage was matched only by their kindness.

"To the people of PNG, I offer Australia's promise: We will never forget."

In addition to the hundreds of Australians killed in PNG, more than 1,600 were wounded along the track.

Mr Albanese's trip to PNG is the longest by an Australian prime minister.

The prime minister will also honour soldiers who fought in other parts of the world, as well as serving members of the Australian Defence Force.

"Decades of war have built a universe of loss, constellations of grief spelt out on tombstones, inscriptions from loved ones aching with all that has been taken, and all that might have been.

"We gather for all who went in our name, and never came home. We gather for all who came home, but never fully left the battlefield. And we thank all veterans. Just as they stepped up for us, we must step up for them.

"We have seen what horrors Australians have defeated. We have seen the difference Australians have made in the world – and continue to make."

In his own Anzac Day message published on Wednesday evening, federal Opposition Leader Peter Dutton said defeats and victories in war had "awakened a national consciousness."

"Just as the Anzac spirit shaped our national soul, our national soul sustained the Anzac spirit," Mr Dutton said.

"And since the First World War, it is a spirit which has characterised Australians whenever and wherever they have served and sacrificed."

He said the "Anzac spirit helped us to prevail in war and prosper in peace … In these difficult times, let us know ourselves again."