The most recent international figures were for 2000, when estimated total emissions were around 4.9 billion tonnes, but China's own data had not been updated since 1994.

The world is gearing up for negotiations on a framework for tackling climate change when the current phase of the emissions-capping Kyoto Protocol expires in 2012, and Beijing's rapidly-rising emissions are in the spotlight.

But China has rejected any concrete caps on its emissions of most gasses, saying development must be its top priority.

However the plan took a tiny first step towards limiting growth with a target to keep industrial production of nitrous oxide steady at 2005 levels through the end of the decade.

A by-product of the nylon and fertiliser industries, the industrial gas has around 310 times the potency of carbon dioxide in trapping heat.

But it accounted for just over 5 percent of the preliminary figure for national emissions in 2004. Officials until recently said China was working on a detailed inventory and did not have even ballpark estimates.

The new figures showed that as China industrialised, and boosted its consumption of coal and oil, the share of carbon dioxide in emissions grew from around three-quarters in 1994 to over 83 percent a decade later.

The other main component was methane, which produced about 12 percent of 2004 emissions, the report said.

China aims to tackle emissions by boosting use of hydropower, wind and biomass energy, pushing use of coalbed methane and nuclear power and increasing the efficiency of coal-burning stations, the plan said.

Together these should lead to a 950 million tonne reduction in carbon dioxide emissions by 2010, while a series of energy conservation plans including better lighting and combined heat and power should cut out another 550 million tonnes.

HIGH OVERALL, LOW PER CAPITA

China has declined to comment on predictions by the International Energy Agency and other economists that it could become the largest global emitter as early as this year.

But if it grows as much between 2004 and 2008 as it did the previous four years, emissions could top 7.5 billion tonnes in 2008, which would bring it within reach of -- if not above -- US levels.

However Beijing has dismissed the comparison as misleading, given China's population is over four times that of the United States so its per capita emissions are well below the levels of all developed nations.

"There is no denying that at some point in time the total emissions of greenhouse gasses from China will overtake those of the United States," said Ma Kai, head of the powerful National Development and Reform Commission which is in charge of climate change policy.

"But when comparing the emissions levels of different countries, one must...not only look at aggregate emissions, but also at per capita emissions," Ma told journalists at a packed news conference, the first by such a senior official on the issue of climate change.