MOSCOW — President Vladimir Putin on Monday cast doubt over the fate of the Kyoto Protocol, which needs Russian ratification to take effect, saying that his country is still undecided and pointing at theories that claim Russia could even benefit from global warming.

Speaking on the first day of the UN World Climate Change Conference in the Russian capital, Putin offered no indication as to when his government might make up its mind about the landmark pact to reduce greenhouse gas emissions.

To go into effect, the 1997 protocol must be ratified by no fewer than 55 countries, accounting for at least 55 percent of global emissions in 1990. After the United States rejected the treaty, the minimum can be reached only with Russia's ratification.

"The government is thoroughly considering and studying this issue, studying the entire complex of difficult problems linked with it," Putin said. "The decision will be made after this work has been completed, and of course it will take into account the national interests of the Russian Federation."

Pressed by some of the conference's delegates for a commitment to ratification, Putin responded ambiguously, citing domestic critics of the Kyoto pact who theorized that Russia could even profit from global warming. He added, however, that Russia may see some adverse effects too.

"They often say, half-jokingly and half-seriously, that Russia is a northern country and if temperatures get warmer by two or three degrees Celsius, it's not that bad — we could spend less on warm coats and agricultural experts say that grain harvests would increase further," Putin said with a grin. "That may be so, but we must also think about the consequences of global climate change.

"We must think what consequences of these changes we will face in certain regions where there will be droughts and where there will be floods," he added. Russian officials must consider "what consequences there will be for people living in these regions; social, economic and environmental consequences."

The Kyoto Protocol calls for countries to reduce their level of greenhouse-gas emissions to 1990 levels by 2012. If a country exceeds the emissions level, it could be forced to cut back industrial production.

Russia's emissions have fallen by 32 percent since 1990 largely due to the post-Soviet industrial meltdown, but slowly emissions have started to rise again amid the economic revival of the past few years.

Putin's ambitious goal of doubling Russia's gross domestic product by 2010 might come into conflict with the Kyoto Protocol, requiring Russia to launch a costly overhaul of its industries in order to cut emissions and thereby slowing down economic growth.

Putin said Monday that the interests of all countries must be taken into account in setting pollution limits, which he said should not strangle economic development.

Putin's comments marked a backward move from Prime Minister Mikhail Kasyanov's pledge a year ago that Russia would ratify the Kyoto Protocol in the "very near future." But it was not entirely unexpected.

The government must submit ratification documents to parliament, and officials had already said that the legislature was not likely to review the issue before the Dec. 7 parliamentary elections.

UN and European backers of the Kyoto Protocol had hoped Russia would commit to ratification while hosting the Moscow conference, and some openly voiced their disappointment.

Klaus Toepfer, the executive director of the UN Environmental Program, warned that while some nations could reap some temporary benefits from global warming, "at the end of the day we will only have losers."