BEIJING, Nov 21 (Reuters) - An underground coal fire in remote northwest China that has raged unchecked for more than 50 years has finally been put out, state media reported on Wednesday.

More than 12.43 million tonnes of coal had been consumed in the fire and an estimated 651 million tonnes saved at the Terak field in Urumqi, capital of Xinjiang autonomous region, the Coalfield Fire Fighting Project Office was quoted as saying.

Often smouldering in coal seams on or just below the surface, the fires have shaped the landscape of Xinjiang for millennia.

The layers of coal can go on for miles underground, which means they have fuel to burn for decades or centuries.

The smoke darkens already polluted skies, the fires emit poisonous gases, and can even make the earth cave in -- swallowing roads, homes, animals and humans -- when weak ash replaces firm coal underground.

Now the government wants to extinguish the fires which are also wasting resources in a rapidly developing country which relies on coal for about three-quarters of its energy.

"First, we drilled into the burning coal bed and then poured water and slurry into it to lower the temperature," Miao Pu, head of the fire fighting team, was quoted by Xinhua news agency as saying.

"After the temperature dropped, we covered the surface to starve the fire of oxygen."

Xinjiang is China's second largest coal producer after the northern province of Shanxi, producing 50 million tonnes annually. The Terak field is the region's second largest coalfield.

(Reporting by Beijing newsroom; editing by Nick Macfie)

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