Formerly a colony of Australia, Papua New Guinea is celebrating 50 years of independence. (Mick Tsikas/AAP PHOTOS)

A defence treaty with Papua New Guinea would bring the relationship with Australia’s closest neighbour even closer, the prime minister says, despite delays in putting pen to paper.

Anthony Albanese is in Port Moresby as PNG marks its 50th anniversary, with more celebrations to take place on Tuesday.

The anniversary is set to coincide with Australia and PNG agreeing to a new landmark security agreement, although it has yet to be formally signed off.

The prime minister said the treaty would be significant.

“This agreement, that’s going through the processes here in PNG, will just take that partnership to the next level,” he told ABC TV on Tuesday.

“It will be a treaty similar to the relationship that we have with the United States.”

Mr Albanese said PNG’s cabinet had not signed off on the agreement as there were’nt enough members present to do so, due to the celebrations.

But he is confident the deal would go through.

“This will be seminal in our relationship with Papua New Guinea, our closest neighbour and one of our dearest friends,” he said.

“We’re respecting the processes of Papua New Guinea and letting them go through their processes. That’s really important, that we respect their sovereignty.”

Pacific Minister Pat Conroy said discussions on the treaty would take place on Wednesday, once anniversary celebrations have concluded.

“This is an important affair and we’ll get to it,” he told ABC Radio.

“We’re not like other countries. We don’t come in and try and close our will on the Pacific family.”

Mr Albanese told Nine’s Today program neighbouring countries in the region, such as Indonesia, had been consulted on the security agreement.

Australia will help PNG build a new ministerial wing onto its parliament, as a gift to mark 50 years of the nation’s independence.

Stream the best of Fiji on VITI+. Anytime. Anywhere.