WASHINGTON (BLOOMBERG) - As leaders from across the globe began a virtual summit discussing issues from the coronavirus pandemic to climate change, Donald Trump's thoughts were elsewhere - on the tussle over the US election.

The president kept his head down, staring at something on his desk out of sight during a nine-minute speech on Saturday (Nov 21) by Saudi King Salman bin Abdulaziz, who welcomed countries taking part in a meeting of the Group of 20 nations hosted by his kingdom.

The speech and footage of other leaders was shown live on the official G-20 website.

Then, within moments of the monarch ending his remarks, Mr Trump tweeted to comment on an encounter with Republican leaders of the Michigan state legislature.

He promised: "We will show massive and unprecedented fraud!"

Mr Trump's post was in response to a tweet by Michigan Senate Majority Leader Mike Shirkey, who met Mr Trump at the White House on Friday along with House Speaker Lee Chatfield.

"We have not yet been made aware of any information that would change the outcome of the election in Michigan," Mr Shirkey and Mr Chatfield wrote in a joint statement.

Mr Trump went on to send further tweets alleging voter fraud and commenting on his son, who has been diagnosed with Covid.

That's even as leaders continued their discussions in private. The optics underscored Mr Trump's disinterest in such forums, with the president often clashing with other leaders during the past four years, especially on issues such as multilateralism, climate change and international trade.

Mr Trump subsequently gave his own opening remarks to the summit, where he said the US under his watch had made the world safer, strengthening Nato and fighting terrorism, according to a European official with knowledge of the proceedings.

He claimed America had been efficient in fighting the pandemic while touting low unemployment and what he said was surging demand in the US economy.