The outage at Japan's biggest nuclear power station was likely to have pushed up manufacturers' CO2 emissions in the year ended last month, despite a slowdown in economic activity, a government official said on Friday.

Carbon dioxide emissions from manufacturers, Japan's main polluters, rose 1 percent in the year to March 2008, a nationwide survey on top greenhouse gas emitting factories and offices showed on Friday. That was far slower than a 12 percent rise in the utility sector.

Japan's greenhouse gas emissions in the year just ended are being closely watched as 2008/2009 was the start of the country's five-year period of the Kyoto Protocol, the current U.N.-led global climate pact under which many nations aim to reduce emissions.

It's hard to predict the impact on the manufacturing sector in fiscal 2008/09 from a significant rise in per unit emissions to calculate their energy-origin CO2 emissions, said Hiroyuki Yamamoto, a deputy director at the Environment Ministry's climate change policy division.

This makes it hard to make predictions despite a fall in the sector's production due to an economic slowdown, he said.

Japanese industry has been struggling to meet its target for carbon emission cuts as Tokyo Electric Power Co's Kashiwazaki nuclear plant has been out of service since an earthquake in 2007. It has raised the use of fossil fuels.

The Federation of Electric Power Companies in Japan has said the sector on average produced 0.453 kg of CO2 emissions per kilowatt hour in the fiscal 2007/08, up 10.5 percent from 0.410 kg a year earlier, in part due to the nuclear outage.

The government released data on emissions of individual manufacturers for the second time. The first such data was released in March 2008 for the 2006/2007 year to encourage individual companies to fight climate change.

The data for the 2007/2008 year, which finished at end-March last year, was topped by steel makers.

Nippon Steel Corp was the No.1 polluter, with 63.1 million tons of energy-origin CO2 emissions, up from 60.3 million tons a year earlier.

It was followed by JFE Steel Corp, Sumitomo Metal Industries Ltd and Kobe Steel Ltd.

Taiheiyo Cement Corp came fifth, and Nippon Oil Corp, sixth.

The utility sector, including electricity, gas, fuel and water, pumped out a total 439.0 million tons, up 12 percent from the previous year.

VOLUNTARY TARGETS

Unlike Europe, which imposes a mandatory cap-and-trade scheme of emissions on individual factories and offices, Japan has encouraged voluntary pledges from industries to meet its Kyoto commitments.

Factories and offices that pump out 3,000 tons or more of CO2 equivalent per year are required to report these amounts annually, using the previous year's per unit emissions level given by their energy suppliers, such as energy-origin CO2 emissions per kilowatt hour.

The pledges, aiming to meet Japan's goal to cut emissions by 6 percent from 1990 levels over the five-year period, are not legally binding. But missing the target would require a company to pay a penalty to the government in the form of U.N. approved emission credits or locally-traded emissions offsets.