The two superpowers could not agree on what to say in the official communique from Asia Pacific Economic Cooperation meeting in Port Moresby on Sunday.

Instead meeting chair Papua New Guinea was forced into announcing the broad consensus of the meeting, rather than the usual official statement.

It's understood China and the US could not agree on language about reforms to the World Trade Organisation, and China opposed levelling the playing field against state-owned enterprises.

Australia was walking a fine line between its largest trading partner and its long-time security ally at the summit, but Prime Minister Scott Morrison played down suggestions relations are fractured.

"I think there is a lot more pragmatism going on here than people have been prepared to acknowledge in the commentary," Mr Morrison told reporters in Port Moresby on Sunday.

"There's a lot of movement under the water."

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China and the US traded verbal blows on Saturday in keynote speeches, with the US urging countries not to sign up for huge foreign debts, and China promising there was no hidden agenda with its infrastructure program.

Chinese officials also reportedly stormed into PNG Foreign Minister Rimbink Pato's office on Saturday demanding he change the wording of an official communique, which he refused to change.

Mr Morrison said the trade war between China and US was hurting global economic growth, but he believed both sides wanted to find a resolution.

"I think they're fully aware, because these things also impact their economies," he said.

Australia and the US will jointly host a naval base on Manus Island, creating a new staging point into the contested South China Sea.

Mr Morrison would not confirm how much the expanded Lombrum naval base would cost, but said Australia was there at the invitation of the PNG government.

He had a brief but "warm" meeting with President Xi Jinping on Saturday night, but the naval base did not come up.

"We were focused on our relationship and what we were doing together," Mr Morrison said.

Australian Associated Press