India’s leader Narendra Modi will attend the UN Cop26 climate summit in Glasgow, it has emerged.

Mr Modi will join other world leaders including US President Joe Biden and Prime Minister Boris Johnson at the talks, where countries will be under pressure to increase action on climate change – although the leaders of some major polluting countries are set to the skip the event.

The news comes after documents leaked in the run up to the conference showed countries lobbying for changes to a UN report making recommendations on how the world should tackle climate change.

But scientists involved in the major science assessments conducted by the UN’s Intergovernmental Panel on Climate Change (IPCC) said the reports’ authors strongly resisted political pressure.

Documents, leaked to Unearthed, Greenpeace’s team of investigative journalists, names countries including Australia and Saudi Arabia as those trying to get the IPCC to weaken a conclusion that fossil fuels should be phased out.

Brazil and Argentina have also reportedly made comments pressing IPCC report authors to delete messages about the climate benefits of undertaking a “plant-based” diet, despite a study in 2018 finding that moving to a meat-free diet could cut food land use, and reduce emissions by 49%.

And the Australian government asked to be deleted from a list of the world’s major producers and consumers of coal, despite being the fifth largest coal producer, Unearthed said.

The process of putting draft reports out for government and expert review is part of the cycle that IPCC climate science assessments go through.

The final draft of each report is published after it has been approved unanimously line-by-line in sessions between government representatives and scientists.

The leaked documents include more than 32,000 submissions made by governments, companies and other interested parties, on the draft report of the IPCC’s working group III section of the UN body’s sixth assessment of climate science.

The working group III report, due to be published next year, is responsible for assessing responses and solutions to climate change, by reducing emissions and enhancing “carbon sinks” such as forests.

Unearthed reports that the majority of contributions were “constructive comments” aimed at improving the report.

A spokesman for the IPCC said processes used when drafting reports were “designed to guard against lobbying from all quarters.”

And UK scientists involved in the process rejected the idea they would be swayed by political lobbying.

Prof Piers Forster, professor of climate change and Priestley Centre director, University of Leeds, said: “In my over 20 years’ experience of writing IPCC reports there has always been lobbying from multiple directions.

“It is important to note that the authors get the last word as ultimately the report rests on peer reviewed science, not opinion.”

He said governments eventually agree the text unanimously, making it the trusted source of climate science for all countries.

“This would not be possible unless all countries felt free to air their views and have them respected, listened to and responded to by the authors.”

Prof Richard Betts, head of climate impacts research at the Met Office Hadley Centre, said: “IPCC reports are scientific documents and the authors respond to review comments on the basis of their scientific merit.

“It’s important that government representatives can comment on the science, and very often they make valid, useful suggestions based on their own knowledge of the literature, but IPCC authors are keenly alert to the possibility of political pressure and strongly resist it.”

The leaks come ahead of the Cop26 conference, where countries face calls to increase action to cut emissions and prevent global warming of more than 1.5C of above pre-industrial levels, beyond which the most dangerous impacts of climate change are expected.

In the summer, the IPCC published the first part of its sixth assessment – after approval by governments – which issued a stark warning on how people were driving dangerous climate change.

The report was labelled a “code red for humanity”.

Commenting on the leaked documents, Greenpeace International executive director Jennifer Morgan, said: “This is an insight into how a small group of coal, oil and meat producing countries continue to put the profits of a few polluting industries before science and our planet’s future.

“Rather than phasing out fossil fuels and unsustainable meat production, they are using every opportunity to protect their corporate interests and continue with business as usual while the planet burns.

“As the global spotlight moves to Glasgow, other world leaders should be aware of how far these governments will go to sabotage our chances of keeping 1.5C in sight.

“The key test for world leaders is whether or not they agree to rapidly phase out fossil fuels, as the science warrants.

“History will not be kind to them if they fail – and we will be watching,” she warned.