Ghana’s former President John Mahama has called the decision by US President Donald Trump to withdraw from the 2015 Paris agreement on climate change as “unbelievable” and a “very sad day for global co-operation”.

Mr Mahama was among world leaders who backed the historic agreement, promising to implement measures to curtail global warming.

He tweeted that the US had abdicated its leadership role in the world.

Mr Trump said the accord “punished” the US and would cost millions of American jobs.

“I was elected to represent the citizens of Pittsburgh, not Paris,” he said.

The Paris agreement commits the US and 187 other countries to keeping rising global temperatures “well below” 2C above pre-industrial levels and “endeavour to limit” them even more, to 1.5C.