"Being pragmatic and understanding host countries' domestic policies and competitive advantage of homegrown companies is one thing," said Len Homeniuk, CEO of Canada's Centerra Gold, which runs mines in Central Asia and elsewhere.

Analysts say the biggest risk lies ahead, with next year's tender for the potentially strategic gold deposit of Sukhoi Log in Siberia.

But foreign miners, previously keen on Sukhoi Log -- contains more than 1,000 tons of gold -- are now taking a cooler approach.

"It doesn't come into our scale of things. Our aim is to be a million-ounce producer. ... And then we'll go from one to two. But we are doing it step by step," Hambro said.

The new subsoil law, yet to be approved by the State Duma and signed by Putin, is expected to become law as soon as this year and will likely allow foreign companies to take minority interests in developing new strategic deposits.

Some analysts have praised it for having a more innovative and transparent approach to holding tenders.

"Coming from Canada, where the government often intervenes in the economic sphere to protect national interests, I am not surprised," Centerra's Homeniuk said.

But it is still proving hard for investors to swallow the law, and will further mar Russia's investment climate, already hit by the Kremlin's breakup of oil major Yukos.

Russian mining companies themselves are also worried because the foreign participation ban may undermine their ability to cooperate with Western majors when developing Russia's most lucrative -- and costly -- deposits.