Putin had set the tone at the opening on Monday with his statement that Russia was as yet undecided and would make up its mind "in line with its national interests."

On Friday he reaffirmed Moscow's reticent stance, saying Russia's economic growth was more important that any benefits the country could derive from greenhouse gas emissions trading -- a key mechanism of the protocol.

In principle, Russia is one of the major beneficiaries of the Kyoto accord, since the low level of pollution of which its depressed post-Soviet industry is now capable gives it massive scope for trading in emission quotas authorised by the treaty.

But Putin said: "Today we are able to sell quotas."

"We hope that in the future we won't have this opportunity, ... we are hoping for economic growth in Russia and do not want to make a decision based on financial gain (from the sale of quotas)," he said, speaking at a gathering of the World Economic Forum.

"We have signed the Kyoto protocol. It is a step in the right direction. But specialists have to examine the problems that Russia could face" if it ratifies the treaty," he said, as quoted by the RIA Novosti news agency.

Under the greenhouse gas trading system, industrial countries that are over their Kyoto emissions target can purchase quotas from industrial signatories that are under their target.

The point of this is to provide a financial incentive for countries to curb their pollution.

If countries have to spend a lot of money to purchase quotas, or like Russia can make money by being under quota, that in theory would be a big spur for them to clean up their act.

Russia's ratification is essential for the Kyoto protocol, which aims to reduce the emission of greenhouse gases held responsible for global warming, to come into force.

The conference attended by 1,200 experts from 43 countries opened to a chorus of calls from European officials, and one from UN Secretary General Kofi Annan, urging Russia to ratify the protocol as soon as possible.

Putin's opening comments were greeted with dismay, German delegation chief Enno Harders describing them as "a step backwards" from a commitment given by the Russian president last year to sign up to the treaty.

Joke Waller-Hunter, executive secretary of the UN Framework Convention on Climate Change (UNFCCC), said she had "hoped for a more precise signal" on when Russia would be ready to ratify the protocol, because "our process on climate change is really waiting for that."

As Russian Greenpeace official Natalia Olefirenko noted, Putin's address "set the tone for the whole conference," and things did not get better over the week.

Some Russian officials appeared determined to find good points to the global warming that, in the view of most experts, represents a serious threat to the global environmental.

Yury Izrael, co-organiser of the conference and head of Russia's Global Climate and Ecology Institute, raised the prospect of "saving on heating costs in winter and extending the period of plant vegetation in agriculture."

Putin's economic advisor Andrei Illarionov told the conference that the protocol could restrict Russia's economic growth, ignoring economic projections by the United Nation that indicate that by 2010, and even by 2020, Russia's emissions are likely still to be below the threshold set by the Kyoto accord.

He said the pact was "discriminatory" against Russia and could prevent it from achieving Putin's goal of doubling gross domestic product over the next decade.

European capitals, among the strongest supporters of the treaty, have offered Russia massive investments in clean technology within the framework of the protocol.

Russian interest in the quota trading system has waned since the United States pulled out of the protocol when President George W. Bush took office in

The withdrawal of the United States, the world's biggest single carbon polluter, means that Russia today has lots of "hot air" to sell but has no significant buyer.

SPACE.WIRE