The ministry said benchmark Urals oil would be priced at $54.8 per barrel on average in the fourth quarter of 2008.
Finance Minister Alexei Kudrin said earlier Russia would retain a budget surplus with an average oil price of $70 per barrel, and that there would be no need to unlock the country's Reserve Fund, designed to cushion the federal budget against a plunge in oil prices.
The economics ministry said its basic forecast for 2009 was based on the price of $50 per barrel, although experts said the possibility of a budget deficit remained if the government failed to cut expenditure.
Kudrin said the country could face a 1 trillion rubles ($36 billion) budget deficit next year.
World oil prices have fallen by more than 60% from a record high of $147 per barrel in July to under $50, as the global credit crunch has reduced demand for fuel.
