* Wildfires cover area size of Belgium
* Greenpeace says drifting smog poses threat to health
* Regional governor says natural phenomenon in remote areas
By Tom Balmforth
MOSCOW, July 30 (Reuters) - More than half a million Russians have demanded the authorities do more to tackle vast wildfires in Siberia that environmentalists have dubbed an ecological catastrophe, but which officials have said would be "pointless" to put out.
Wildfires cover almost 3 million hectares of forest, an area almost the size of Belgium, according to the Federal Forestry Agency, and have prompted states of emergencies to be declared in five Russian regions.
Greenpeace said on Monday that acrid smog had wafted across Siberia as far as the Ural mountains, posing a threat to people's health.
"The situation with the forest fires in Siberia has long ceased to be a local problem and has turned into an ecological catastrophe on the scale of the entire country," Greenpeace wrote on social media on Monday.
A petition circulated online by an ecologist from the Siberian city of Tomsk had garnered 724,000 signatures as of Tuesday calling on authorities to take tougher action and to declare a Siberia-wide state of emergency.
The petition has no binding powers, but its author hoped public pressure would translate into government action.
Firefighters are working to put out forest fires covering almost 100,000 hectares in Siberia's Irkutsk and other regions, but other wildfires raging on 2.8 million hectares are only being monitored, the Federal Forestry Agency said on Tuesday.
Authorities have said they do not plan to expend resources on fighting the latter as they are mainly in remote, uninhabited areas - known as "control zones" - and therefore not a direct threat to people.
"This is a normal, natural phenomenon, it's pointless to fight it and perhaps even in some places also harmful," the governor of Krasnoyarsk region, Alexander Uss, was quoted as saying by RIA news agency on Monday.
Uss said sending firefighters would put their lives at risk because of thick smoke and the sheer remoteness of the fires.
Greenpeace, however, said the authorities were wrong to say the fires, which have been burning for several weeks, affected only uninhabited parts of the country.
"There are people there! The lines of the control zones fall in such a way that settlements fall within them," it said.
(Editing by Alison Williams)
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