"We are against coal conversion for one reason -- out of all fossil fuels, coal contributes most to climate change, emits the most carbon dioxide," Legambiente President Roberto Della Seta told Reuters.

Italy's emissions of the greenhouse gases that are widely blamed for global warming have risen 12 percent since 1990, rather than heading towards the 6.5 percent reduction that it has pledged to reach by 2012 under the Kyoto Protocol.

Della Seta said conversion of power stations to coal would move Italy farther away from the Kyoto Protocol targets.

Enel says the so-called "clean coal" technology it uses in conversion allows it to reduce emissions of carbon dioxide (CO2) and other gases and particles to well below required levels.

CHEAP COAL

Coal is also cheap and helps to diversify Italy's energy supplies, which are some 90 percent reliant on oil and gas imports.

Della Seta said the new technology may help reduce emissions of other gases, but not CO2.

"Enel cannot change a law of physics which says that CO2 emissions per every kilo of burned coal are greater than per kilo of oil and much greater than per kilo of gas."

Della Seta said Legambiente, which is one of Italy's main green groups, supported activists who went on a hunger strike in March protesting against Enel's plan to convert to coal a 2,600 megawatt oil-fired power station at Civitavecchia near Rome.

Italy's Environment Ministry last month called for a revision of a permit given to Enel's Civitavecchia project, after the hunger strike raised concerns about the health situation in the nearby district.

Enel has said the Civitavecchia station respects environmental and health standards.

Della Seta said in the interview last week that Legambiente opposed another Enel plan, to convert a similar power station, Porto Tolle in northern Italy.

"We think Italy should not increase the percentage of coal in its fuel mix, but instead, it should move in other directions: gas, renewable source, energy efficiency," he said.