US President Donald Trump has canceled a planned meeting with Russian President Vladimir Putin at this weekend’s G20 summit injecting more drama into what promises to be a tense gathering of world leaders.

Most of the focus in Buenos Aires will be on Mr Trump’s talks with Chinese President Xi Jinping on Saturday, as world markets hope for a cooling of the escalating trade war between their two nations.

Prime Minister Scott Morrison has left for the summit without his deputy Josh Frydenberg who pulled out to deal with domestic political issues, and with no scheduled meeting with the US leader.

Despite not being included on Mr Trump’s formal program, Mr Morrison hinted he could meet with the US President over the weekend.

“Watch this space, as he [Mr Trump] would say,” the Prime Minister told reporters in Canberra before leaving for Buenos Aires.

Mr Trump cited Russia’s seizure of Ukrainian vessels as his reason for pulling out of planned talks with Mr Putin.

In a Tweet from Air Force One en route to Argentina, the US President said: “The ships and sailors have not been returned to Ukraine from Russia.”

He added: “I look forward to a meaningful Summit again as soon as this situation is resolved!”

But more importantly, China is looking for “positive results” in resolving a trade dispute with the US ahead of the closely watched meeting of Chinese and US leaders.

Asked if China was seeking to prevent the imposition of additional US tariffs at the high-stakes meeting, China’s commerce ministry spokesman, Gao Feng, said economic teams from both nations were in contact to implement a “consensus” reached by Mr Trump and Mr Xi during a phone call this month.

“I hope that the United States and China could move towards each other and work hard to achieve positive results in the meeting,” Mr Gao said on Thursday night, without giving any details.

The imposition of US tariffs on Chinese exports has been blamed for much of the instability in global stock markets in recent weeks.

The US has levied additional duties of between 10 per cent and 25 per cent on US$250 billion ($340 billion) worth of Chinese goods this year as punishment for what it calls Beijing’s unfair trade practices, with the 10 per cent tariffs set to climb to 25 per cent next year.

“The Chinese side has repeatedly stressed that the essence of Sino-US economic and trade co-operation is about mutual benefit and win-win,” Mr Gao said.

White House officials said this week Mr Trump was open to making a trade deal with Mr Xi when they meet.

As well as trade, many leaders will be seeking to talk to Saudi Crown Prince Mohammed bin Salman, who will be attending the summit, amid concerns about the murder of Washington Post columnist Jamal Khashoggi.

-with agencies