By James Landale
Diplomatic correspondent
UK government sources confirmed a report in The Times that Mr Johnson had been advised the Chinese leader was not expected to come.
However Chinese officials reportedly have not entirely ruled out a change of plans.
COP26 takes place in Glasgow from 31 October to 12 November.
Leaders from around the world will meet to discuss how to minimise global temperature rises caused by human activity.
President Xi’s attendance at COP26 has long been in doubt. It is thought he has not left China since early 2020.
“They want to be seen as green leaders so I wouldn’t rule it out,” one Whitehall source said.
Diplomats said China often announced President Xi’s travel plans at the last minute. One said: “We never give up hope. And we are continuing to make the case for his personal attendance.”
In September, Chinese officials told Italian diplomats that President Xi did not plan to attend a meeting of G20 leaders in Rome on October 30 which immediately precedes the COP26 summit. They cited China’s Covid regulations as the reason.
Western diplomats said there were genuine concerns among Chinese officials at being able to protect Mr Xi from Covid outside China.
On 19 September, the UK COP President Alok Sharma told the BBC’s Andrew Marr show there was uncertainty about President Xi’s attendance: “The issue of whether President Xi Jinping is going to come, that’s not yet been confirmed.”
Australia, a large producer of coal and gas, is ranked poorly for its climate policies and emissions reductions. One report put it last for climate action out of 193 UN member nations.
The country is under pressure to commit to stronger and faster change.
China may not be only absentee
President Xi might not be the only world leader who skips the summit.
No major leader – aside from Pope Francis, who said he had hoped to go, but recently underwent colon surgery – has said they definitely won’t be attending the COP26 summit in November.
But some have expressed doubts about attending – including leaders from some of the world’s biggest carbon emitters.
Russia has set a goal of reducing greenhouse gas emissions to 70-75% of 1990 levels by 2030.
President Jair Bolsonaro of Brazil and President Narendra Modi of India are yet to confirm their attendance, after missing the last summit.
At the last COP meeting in 2019, the heads of the world’s top five emitters – China, India, Japan, US and Russia – all failed to attend.