* Japan waters down CO2 emissions target after Fukushima
* Says move inevitable after nuclear power plants shut
* Chinese talks delegate: 'No way of describing dismay'
* European Union, campaign groups among Tokyo's critics (Adds reaction from U.N. climate talks in Warsaw)
By Elaine Lies and Stian Reklev
TOKYO/WARSAW, Nov 15 (Reuters) - China, the EU and campaign groups criticised Japan at U.N. climate talks on Friday after Tokyo slashed its target to cut greenhouse gas emissions, blaming its shuttered nuclear power industry in the wake of the Fukushima disaster.
The Japanese government on Friday decided to target a 3.8 percent emissions cut by 2020 versus 2005 levels. That amounts to a 3 percent rise from a U.N. benchmark year of 1990 and the reversal of the previous target of a 25 percent reduction.
"Given that none of the nuclear reactors is operating, this was unavoidable," Environment Minister Nobuteru Ishihara said.
Japan's 50 nuclear plants were closed on safety concerns after the March 2011 earthquake and tsunami wrecked the Fukushima reactors northeast of Tokyo. Nuclear accounted for 26 percent of Japan's electricity generation and its loss has forced the country to import natural gas and coal, causing its greenhouse gas emissions to skyrocket.
Japan's new policy was criticised in Warsaw, where about 190 nations are meeting from Nov. 11-22 to work on a global climate pact, due to be agreed in 2015.
China's climate negotiator Su Wei said: "I have no way of describing my dismay" about the revised target.
The European Union said it expected all nations to stick to promised cuts as part of efforts to halt global warming.
"This move by Japan could have a devastating impact," said Naoyuki Yamagishi of environmental campaign group WWF Japan. "It could further accelerate the race to the bottom among other developed countries."
Climate Analytics, a think-tank, said replacing nuclear with Japan's current fossil fuel mix would still allow Tokyo to target a 17-18 percent reduction from 2005 levels by 2020.
Japan's decision added to gloom at the Warsaw talks, where no major countries have announced more ambitious goals to cut emissions, despite warnings from scientists about the risks of more heatwaves, droughts, floods and rising sea levels.
Poor nations want the rich to commit to deeper emissions cuts while providing more finance to developing nations to help them deal with the impacts of climate change, a major issue at the talks after the Philippines was devastated by typhoon Haiyan, one of the most powerful ever recorded.
Australia has been criticised for watering down its climate policies, and Brazil reported on Thursday a rise in the rate of deforestation in the Amazon - plants help slow global warming by soaking up carbon dioxide as they grow.
Natural-gas consumption by Japan's 10 utilities was up 8.4 percent in October from a year earlier and coal use was up 4.4 percent as the companies used more fossil fuels to compensate for the nuclear shutdown, industry data showed on Friday.
Prime Minister Shinzo Abe advocates a return to nuclear power, but says he wants to reduce Japan's reliance on it over time. The process of restarting reactors will begin next year at the earliest and some will never come back on line due to safety concerns.
With Abe facing opposition to nuclear power even from within his own party, the weaker emissions commitment could be an argument for restarting reactors, given that Japan for decades has touted the clean energy.
The Japanese delegation got a standing ovation when it arrived at U.N. climate talks in Bangkok in 2009, weeks after then-Prime Minister Yukio Hatoyama announced the 25 percent target, the most ambitious by any major developed nation.
"Our energy mix, including the use of nuclear power, is currently being reviewed. In that context, we decided to set this target at this point," Chief Cabinet Secretary Yoshihide Suga said of the new goal.
Hiroshi Minami, Japan's chief negotiator at the U.N. talks, said the new goal "is based on zero nuclear power" in future.
The nuclear shutdown could prove convenient for Abe in that it allows his government to abandon a target that some said was too optimistic.
"Anyone could have seen that this was just impossible - it was predicated on a nuclear ratio of at least 50 percent," said energy analyst Akira Ishii.
(Additional reporting by Michael Szabo and Alister Doyle in WARSAW and Osamu Tsukimori in TOKYO; Writing by William Mallard; Editing by Ed Davies and Janet Lawrence)