Clashes between the world's top two economies over the rules of global trade blocked agreement on a formal written declaration by the 21 nations represented at the Port Moresby meeting.

Washington had pressed for leaders to issue what amounted to a denunciation of the World Trade Organization and a call for its wholesale reform -- a step too far for Beijing, which would likely suffer in the event of any change to trade rules.

But China on Monday chose instead to focus on the "positive results" of the summit.

"The meeting pushed forward different areas of practical cooperation under the APEC framework," Chinese foreign ministry spokesman Geng Shuang told a regular press briefing, adding that many APEC leaders "clearly expressed that they were against protectionism".

"I think they are standing on the right side of history," he added.

Beijing also denied attempting to barge into the office of host country Papua New Guinea's foreign minister during the summit.

Police were stationed outside of foreign minister Rimbink Pato's office after Chinese delegates tried to enter the office in a last-minute bid to influence the summit's draft statement, according to several sources.

"This is purely a rumour from someone with ulterior motives," said Geng.

"Any plot to undermine China-Papua New Guinea relations will not succeed."

The spat ramps up the stakes for a crunch meeting between US President Donald Trump and his Chinese counterpart Xi Jinping at a G20 summit in Argentina later this month.

In a speech at the APEC summit, Xi lashed out at "America First" trade protectionism, while US Vice President Mike Pence warned smaller countries not to be seduced by China's massive Belt and Road infrastructure programme.

The "opaque" loans come with strings attached and build up "staggering debt", Pence charged, mocking the initiative as a "constricting belt" and a "one-way road".