Hundreds of environmental groups called Wednesday for the issue of loss and damage finance to be on the formal agenda of the forthcoming COP27 UN climate summit in Egypt.

Developing nations have for years called for funding from rich polluters to help them reduce emissions while growing their economies and adapt to the impacts of global heating.

They argue that historic polluters also have a moral imperative to pay for the loss and damage -- impacts already being felt that countries cannot adapt to, such as Pakistan's devastating floods -- that their emissions are accelerating.

At the last UN climate summit, COP26 in Glasgow in 2021, countries representing six out of every seven people on the planet called for the establishment of a dedicated loss and damage "facility" that at-risk nations could instantly access to help them recover from extreme events.

That was shot down by richer nations, however. A loss and damage "dialogue" was offered as an alternative ahead of COP27, which begins in November in Sharm el-Sheikh.

More than 400 aid agencies and activist groups on Wednesday signed an open letter demanding that loss and damage finance be added to the official negotiating agenda.

They said discussions around money for impacted nations was needed "to ensure a meaningful outcome at COP27 to respond to the intensifying suffering of people facing climate and connected crises".

Harjeet Singh, head of global political strategy at Climate Action Network International, said that the conference's credibility was "hanging by a thread".

"The COP27 conference will be counted as a failure, if developed nations continue to ignore the demand from developing countries to establish a loss and damage finance facility to help people recover from worsening floods, wildfires and rising seas," he said.