The "Climategate" row took centre stage on the opening day of the Copenhagen climate summit today as the world's leading oil exporter intervened to question the scientific consensus on man-made global warming.

As 15,000 delegates from 192 nations began what was billed as the "last, best chance" to avert a catastrophic rise in sea and air temperatures, Saudi Arabia's chief climate negotiator, Mohammed al-Sabban, spoke from the floor to say that e-mails hacked from a UK research centre had shaken trust in the work of scientists.

He was not the first to mention the Climategate scandal. In his opening address to the conference, Rajendra Pachauri, chairman of the Nobel prize-winning Intergovernmental Panel on Climate Change (IPCC), said the hackers had been trying to undermine the work of his organisation.

But he said that the science as presented in the IPCC's last assessment report two years ago was clear and incontrovertible and covered water shortages and rising sea levels.

"Given the wide-ranging nature of change that is likely to be taken in hand, some naturally find it inconvenient to accept its inevitability," Dr Pachauri said.

"The recent incident of stealing the e-mails of scientists at the University of East Anglia shows that some would go to the extent of carrying out illegal acts, perhaps in an attempt to discredit the IPCC.

"But the panel has a record of transparent and objective assessment stretching over 21 years performed by tens of thousands of dedicated scientists from all corners of the globe."

The Copenhagen summit, which will eventually involve at least 110 world leaders, including Barack Obama and Gordon Brown, is designed to produce an outline agreement that would succeed the Kyoto Protocol and go far beyond it in scope.

The political deal reached here could bring deep cuts in CO2 emissions from industrialised nations and a "cap-and-trade" programme under which hundreds of billions of dollars would be paid to the developing world.

But policymakers fear a potentially fatal loss of momentum after the publication last month of hundreds of e-mails sent by and to the Climatic Research Unit at the University of East Anglia which appear to suggest a deliberate attempt by the experts to skew the science of global warming.

The university has appointed a respected Scottish civil servant to investigate the scandal and decide whether the science really was skewed. Dr Pachauri has already said that the IPCC would hold its own investigation.

But Mr al-Sabban said that an independent inquiry was needed "especially now that we are about to conclude an agreement that ... is going to mean sacrifices for our economies".

He added: "The IPCC, which is the authority accused, is not going to be able to conduct the investigation."

The Saudi negotiator rejected Dr Pachauri's defence of the IPCC's integrity as "general statements".

"In light of recent information ... the scientific scandal has assumed huge proportion," he said. "We think it is definitely going to affect the nature of what can be trusted in the negotiations."

The summit is being held in a vast congress centre on the edge of Copenhagen, powered by wind turbines – although organisers admit that it will have a significant carbon footprint.

It opened with welcome speeches from the Danish Prime Minister, Lars Lokke Rasmussen, and Ritt Bjerregaard, the Mayor of Copenhagen. As the EU's environment commissioner in the late 1990s, Ms Bjerregaard helped to negotiate the Kyoto Protocol, which pegged back emissions from industrialised nations but has never been ratified by the United States.

"Ladies and gentlemen, the world is depositing hope with you for a short while in the history of mankind," Mr Rasmussen said. "For the next two weeks Copenhagen will be Hopenhagen."

The first week of the conference will be focused on refining the complex text of a draft treaty. But major decisions will await the arrival next week of ministers and the heads of state and government in the final days of the summit.

Among those decisions is a proposed fund of $10 billion (£6 billion) each year for the next three years to help poor countries prepare climate change strategies – in effect, buying their acceptance of a deal. After that, hundreds of billions of dollars would be needed every year to help to restrcit rises in global temperatures.

A study released yesterday by the UN Environment Programme indicated that pledges by industrial countries and major emerging nations fall just short of the reductions of greenhouse gas emissions that scientists have said are needed.