YAKUTSK, Russia (Reuters) - For millennia, extinct mammoths lay undisturbed in the permafrost in Russia’s Yakutia region. They have now turned into a source of wealth, and the local government is keen to start tapping it.

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Mammoth ivory is highly sought after for use in trinkets and jewelry, especially in Asia. The material is promoted by people in the trade as an ethical alternative to elephant tusks.

Monique Pean, a jewelry designer whose clients have included Michelle Obama, the former U.S. first lady, has made some of her collections out of mammoth ivory.

Yakutia, a vast and sparsely inhabited region shrouded for most of the year in snow and ice, is best known as a diamond and gold-mining area, but it is also the source of 90 percent of the world’s supply of mammoth ivory.

Last year, 80 tonnes of fossilized mammoth ivory was gathered in the region, according to Nikita Shepelyov, Yakutia’s deputy minister for industry and geology.

Legislation forbids digging down to excavate frozen mammoths, but anyone who purchases a license - a five-year permit costs 7,500 roubles ($131.49) - can gather mammoth remains from the surface.

In some cases, the spring thaw flushes mammoth carcasses out to the surface. Many professional mammoth collectors speed up the process by using high-powered pumps to disperse the soil.

This practice is illegal, because it harms the environment, but it often goes on unchecked because state inspectors cannot monitor what is happening in remote areas.

The local government wants to change the tax laws so that mammoth tusks can be taxed in the same way as other commodities dug out of the ground, such as gold and diamonds.

“Unfortunately, we don’t receive taxes from this activity (mammoth prospecting),” Yakutia’s president, Yegor Borisov, said on local state-run television.

Shepelyov, the deputy minister, said his ministry wants land containing mammoth remains to be added to a regional register of subsoil blocks, giving the local government more control over the industry.

In Yakutia, a kilogram of the highest-quality mammoth ivory in unworked form will sell for around $430 and higher, depending on the size of the tusk and how well preserved it is.

In Asia, large, polished and cut tusks retail for hundreds of thousands of dollars, and sometimes more, people in the industry told Reuters.

Some green groups disagree that the mammoth ivory trade is ethical. They say there is a risk that it could actually encourage elephant poaching, by allowing traders in illegal elephant tusks to pass off their goods as mammoth ivory.