E-mails hacked from a climate research institute suggest climate change does not have a human cause, according to Saudi Arabia's lead climate negotiator.
Mohammad Al-Sabban told BBC News that the issue will have a "huge impact" on next week's UN climate summit, with countries unwilling to cut emissions.
Scientists say the e-mails from the University of East Anglia do not alter the picture of man-made warming.
Meanwhile, India has set a target for curbing the rise in its CO2 emissions.
Environment minister Jairam Ramesh pledged to cut India's emissions intensity - the amount of greenhouse gases produced for every unit of GDP - by 20-25% by 2020, "if we get support from the international community".
Human impact denied
The e-mails issue arose two weeks ago when hundreds of messages between scientists at the university's Climatic Research Unit (CRU) and their peers around the world were posted on the world wide web, along with other documents.
It appears that the material was hacked or leaked; a police investigation has yet to reveal which.
CRU maintains one of the world's most important datasets on how global temperatures have changed.
Climate "sceptics" have claimed that the e-mails undermine the scientific case for climate change being caused by humanity's greenhouse gas emissions, dubbing the issue "ClimateGate".
But it has not until now materialised as an issue likely to influence the Copenhagen negotiations, which are supposed to agree a new global deal on combating climate change to supplant the Kyoto Protocol.
Saudi Arabia is an influential member of the G77/China bloc which leads the "developing world" side in many elements of the UN negotiations.
Mr Al-Sabban made clear that he expects it to derail the single biggest objective of the summit - to agree limitations on greenhouse gas emissions.