A senior adviser to President Vladimir Putin has cast further doubt on whether Russia will ever ratify the Kyoto agreement on limiting emissions of the greenhouse gases linked to global warming.
Andrei Illarionov, who advises the president on economic policy, was speaking the day after Mr Putin refused to set a timetable for Russian ratification, angering supporters of Kyoto around the world.
Putin: Concerned about cost
So long as Russia stays out, the UN protocol setting targets for cutting emissions from the burning of fossil fuels cannot take legal effect.
Speaking at the World Climate Change Conference in Moscow, Mr Illarionov told BBC News Online: "The words of President Putin cannot be interpreted as saying that Russia will ratify the Kyoto protocol but that it is just a matter of time. He never said that.
"The president said that we are in the process of studying the Kyoto Protocol and all the consequences of it. That will take time. What decision will be taken remains to be seen."
Mr Illarionov, a key member of Mr Putin's inner circle of advisers, went on to question whether it would be in Russia's economic interests to sign up to Kyoto, despite the 30% cut in emissions which have taken place since 1990 due to the collapse of traditional smokestack industries.
He argued that economic growth in Russia would bring its emissions back up to 1990 levels by the end of the decade, so it would not have any spare pollution allowances to sell - rejecting the claim that the country stood to gain financially from the treaty.
And beyond 2012, the end date for the targets agreed at Kyoto, the costs for Russia could start to mount if further cuts in emissions were required.
"It's quite clear that the Russian economy is not going to stop at the amount of carbon dioxide emissions that we have today or that we shall have in 2012.
"That's why it is necessary to calculate the costs which will have to be balanced against any possible gains," said Mr Illarionov.
"The United States and Australia have calculated that they cannot bear the economic consequences of ratifying the Kyoto Protocol. If they aren't rich enough to deal with those consequences, my question is whether Russia is much richer than the US or Australia?"
Mr Illarionov's analysis is challenged by many economists, including some in Russia, but his downbeat comments indicate how difficult it is going to be to persuade Mr Putin to move ahead with Kyoto.
Taken together with a succession of Russian scientists using this conference to cast doubt on the science of global warming, the event is proving something of a nightmare for supporters of worldwide action to combat climate change.