South African President Cyril Ramaphosa says there is "overwhelming consensus" for a Group of 20 summit declaration despite the United States boycotting the event.

G20 envoys drew up a draft leaders' declaration on Friday without US input, four sources familiar with the matter said, in a surprise move a senior White House official described as "shameful".

One of those sources confirmed the draft made references to climate change, despite objections from the administration of US President Donald Trump, who doubts the scientific consensus that warming is caused by human activities.

In opening remarks to the Johannesburg summit on Saturday, host Ramaphosa said: "There's been overwhelming consensus and agreement that one of the other tasks we should undertake right at the beginning is to ..

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