A major defence treaty between Australia and Papua New Guinea has failed to get over the line today, with the countries resorting to signing a communique in lieu of the actual document.

Papua New Guinea's cabinet has not yet approved the treaty, throwing a spanner in the works for Australia, which was hoping to clinch the high-level agreement this week.

The mutual defence treaty would see Australia and PNG commit to defending each other in the event of a military attack.

But Papua New Guinea's foreign minister Justin Tkatchenko told the ABC cabinet approval was still a "work in progress".

He said the treaty had been circulated to ministers and PNG's national cabinet would meet next week. Loading

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