UN Special Rapporteur on the promotion and protection of human rights in the context of climate change Ian Fry has said the major greenhouse emitting countries have a clear obligation under international law to provide funding to help highly vulnerable countries like Bangladesh to recover from the impacts of climate change.

"Bangladesh should not have to carry the burden of climate change alone," the UN expert said on Thursday, calling for an international fund to help the South Asian country to recover from the impacts of extreme weather events.

He visited some of the most adversely affected regions of Bangladesh and said it is clear to him that the burden of climate change should not be carried by Bangladesh alone.

"For too long, major emitting countries have denied their responsibility for the suffering they are causing. This must end," said the UN Special Rapporteur.

In a statement at the end of his 10-day visit to Bangladesh to study the impact of climate change in the South Asian nation, Fry said the international community must immediately establish a loss and damage fund to finance the recovery of climate change-affected States.

Fry said women carried an enormous burden of climate change impacts, walking long distances to fetch fresh water, which put them at risk of sexual harassment and kept them from childcare and farming.

According to the Special Rapporteur, women lost livestock, crops and stored seeds in the flash floods of Sylhet, in northeast Bangladesh, and it would take the community at least two years to fully recover.

During his visit, the UN expert held meetings online with indigenous peoples who expressed grave concerns about their future, as the logging of their land was destroying traditional livelihoods and making it harder to find freshwater, food and medicine.

The logging was a violation of the Bangladesh government's own programme to Reduce Emissions from Deforestation and forest Degradation (REDD+), the Special Rapporteur said.

The government refuses to recognise that these communities are indigenous, and their plight was therefore being ignored, he said.

"The issue of climate change displacement was deeply disturbing for me. Millions of people suffering from hardship caused by climate change are migrating to cities to seek other opportunities," the expert said.

"Inevitably these people end up in the slum areas of the major cities, where their basic rights are being denied," he said.

The Special Rapporteur said he had received reports that the situation of children in urban slums was particularly dire.

"They suffer high rates of malnourishment, school drop-out, child marriage, child labour and abuse," he said.

Fry said he also met with climate change activists who claimed they were being persecuted by the government for protesting against new coal-fired power plants.

"The government appears to be using the Digital Protection Act to suppress the voice of climate activists. This is a gross overreaction. People have the right to express their views without being referred to as 'terrorists', the UN expert said.

Fry will present a report to the UN General Assembly in 2022, focused on the promotion and protection of human rights in the context of climate change mitigation, loss, damage and participation - an issue he said was brought sharply into focus during his visit to Bangladesh.

A full report on his visit to Bangladesh will be presented to the Human Rights Council in June 2023.