The United States. which pulled out of the Kyoto Protocol in 2001, said its policy of promoting \"breakthrough technologies\" for energy was the \"only acceptable cost-effective option\" to limit gases blamed for heating the planet.
\"(Kyoto is) an unrealistic and ever-tightening regulatory straitjacket, curtailing energy consumption,\" Paula Dobriansky, U.S. undersecretary of state for global affairs, wrote in the Financial Times newspaper.
But government ministers meeting in Milan for a 12-day effort to breathe some life into the protocol, said they were still hopeful Russia would change lanes and sign on next year, allowing it to take effect.
Russia\'s ratification would allow the Protocol to meet its goal of representing 55 percent of industrial countries\' emissions.
\"Most of the parties have great hopes that Russia will fulfil her obligations,\" said Hungarian Environment and Water Minister Miklos Persanyi at a news conference.
\"It was promised by responsible politicians of the Russian Republic.\" Persanyi has been named to head up the talks for the next year.
China, France and an allied block of developing nations also urged Russia yesterdayto get on board.
Russia has been coy about its intentions, and environmental groups do not expect a decision until after presidential elections next year.
Kyoto aims to cut carbon dioxide emissions by five percent from 1990 levels by 2008-12 as a first step to limit rising temperatures blamed for climate change and more frequent floods, droughts, heat waves and storms.
But the U.N. body overseeing the talks has warned that industrialized nations\' emissions could rise by eight percent from 2000 until 2010 - a 17 percent rise from 1990 levels. Bureaucrats and scientists will spend much of the December 1-12 conference trying to set final details of the Protocol.
Some 80 ministers are due to attend the high-level portion of the talks - to focus on how forest projects can help countries meet their Kyoto commitments - from December 10.
The United States, whose emissions could rise by one-third between 1990 and 2010, aggressively defended its go-it-alone approach, sending a large delegation and questioning the need for tight regulations as well as the science supporting the treaty.
\"Where we are today in climate change science is problematic,\" said Conrad Lautenbacher, undersecretary of commerce for oceans and atmosphere, at a news conference. \"We need more fundamental understanding.\"
Climate policy chief of the WWF environmental group, Jennifer Morgan, said America was trying to torpedo the talks.
\"The White House delegates are coming to Milan to undermine this treaty, even though President (George W.) Bush pledged not to block other countries from moving forward,\" she said.
(Additional reporting by Cristiano Corvino in Milan, Alister Doyle in Oslo and Mark John in Paris)