Russia will bar foreign-owned companies from bidding for the country's most lucrative natural resources this year in the most explicit and sweeping manifestation of a nationalistic state policy developed under the presidency of Vladimir Putin.

The Ministry for Natural Resources said companies would have to be at least 51 per cent Russian-owned to take part in this year's tenders for strategic oil and metals deposits. The rule may prevent oil companies such as ExxonMobil and ChevronTexaco from developing new Russian oil reserves, and also stymie TNK-BP, a pioneering 50-50 owned Anglo-Russian oil company.