Leaders of the world’s 20 biggest economies have agreed to tackle "the critical and urgent threat of climate change” but angered activists by offering few concrete commitments to limit global warming.

Wrapping up a summit in Rome, the leaders of the G20 pledged on Sunday to stop funding coal-fired power plants in poor countries, but set no timetable for phasing it out at home.

They agreed to cap the global rise in temperature to 1.5C (2.7F) above the pre-industrial average but made only a vague commitment to seek carbon neutrality "by or around mid-century”.

This was the result of days of tough negotiation among diplomats, and it leaves huge work to be done at the broader United Nations COP26 climate summit in Scotland, which starts this week.

While Italian Prime Minister Mario Draghi and French President Emmanuel Macron described the G20 as a success, the outcome disappointed the chief of the UN as well as the leader of the United Kingdom.

Draghi said the declaration went further on climate than any G20 statement before it. He noted that it referred to limiting global warming at the 1.5C threshold that scientists say is vital to avoid disaster.

"We changed the goalposts,” Draghi told reporters.