Negotiators were pushing on with clearing away some of the finer technical points scattered around Kyoto's notoriously complex rulebook, diplomats said.

But the biggest question of all remained unanswered: whether the accord, born in the Japanese city of that name six years ago, will at last take effect or be left to gather dust as a relic of environmental law.

Russia, which holds Kyoto's future in its hands under the accord's ratification arithmetic, raised new doubts on Thursday.

It voiced objections to rules on foreign investments in clean technology, an area where its sputtering economy has a keen interest, and demanded further negotiations.

"This and a number of other obligations have significantly changed the conditions under which we could possibly participate in the Kyoto Protocol in its present form," Russian delegation chief Alexander Bedritsky warned.

Kyoto was agreed as a "framework" agreement in 1997, setting down the goals by which industrialised countries, but not poorer ones, would reduce their emissions of fossil gases by 2008-2012 as compared with their 1990 levels.

It took four years of bitterly-fought talks for a deal on its rulebook, as nations wrangled over untested ideas such as a market in carbon emissions.

At times, they were embroiled almost literally in tree-counting -- "forest sinks" that soak up carbon dioxide and could thus be offset against national pollution outputs.

A crippling blow was dealt in March 2001 when the United States walked out, in what was one of President George W. Bush's first acts in office, and this stripped the Protocol of the world's biggest polluter and carbon-market player.

Friday's negotiations focused on two funds -- one for developing countries, the other for the least developed countries -- to help these nations adapt to climate change.

Kazakhstan, Ukraine and Venezuela on Thursday pledged they would soon join 120 other nations that have ratified Kyoto.

The 12-day Milan marathon, gathering 188 states and other UN members, included a two-day meeting of environment ministers, gathered under the auspices of Kyoto's parent treaty, the UN Framework Convention on Climate Change (UNFCCC).

Among its highlights were new data about the cost, in health and economic terms, of climate change.

A report by the World Health Organisation (WHO) said changing weather patterns would unleash outbreaks of diarrhoea, malaria and dengue fever in vulnerable countries, while swathes of southern Asia could be hit by malnutrition because of the effects on agriculture.

And reinsurance giant Munich Re estimated natural disasters, most of them caused by extreme weather, cost the world more than 60 billion dollars in 2003, up 10 percent over 2002.

The UN's top scientific body on global warming, the Intergovernmental Panel on Climate Change (IPCC), believes the Earth's average surface temperature increased by about 0.6 C (1.08 F) during the 20th century, of which two-thirds has occurred since 1975, when the effects of the age of oil began to kick in.

It projects a rise of between 1.4 and 5.8 C (2.5-10.4 F) from 1990-2100, with the variation depending on how much action is taken to curb greenhouse-gas emissions.

At the top end of the IPCC's estimates, sea levels could rise by 88 centimetres (55 inches), drowning many small island states and delta regions.

SPACE.WIRE