A decade-old target for rich countries to contribute $100 billion a year to help poorer ones fight climate change should be attainable in 2023, ministers said on Monday ahead of the COP26 summit.

The target was meant to have been reached last year, and the failure of developed nations to do so has become a key point of contention heading into the summit starting next week in Glasgow.

The UK government's COP26 president, Alok Sharma, had tasked the environment ministers of Canada and Germany to review pledges so far, and they pointed to a "positive trend" in a new report.

"So our work continues, but we have reached a significant milestone today, one that I hope will start to restore trust and build momentum in this final stretch ahead of COP26," Sharma said at the report's unveiling.

The ministers said analysis by the Organization for Economic Co-operation and Development (OECD) showed "significant progress towards the $100 billion goal in 2022 and provides confidence that it would be met in 2023".

Sharma stressed the work on helping poorer nations adapt to and mitigate for the worst impacts of climate change was "far from complete".

"Crucially, we must increase the sums available for climate adaptation and we must also urgently improve access to finance," he said.