Oil prices are not formulated but are regulated according to market trends, said Ksenia Yudaeva, Russian sherpa to the G20 group of large economies, said on Dec 14.

China and Russia signed several energy deals earlier this month but have since not agreed on gas supplies amid a disagreement over prices.

"What we will consider is energy regulation on oil markets and effectiveness in terms of investment," she said at a news conference.

Russia, the world's largest energy producer, and China signed agreements to cooperate on coal and electricity projects following meetings between top leaders of both countries in Moscow on Dec 5.

The two countries have been boosting energy cooperation over the past several years, but, because of disagreements over prices, have repeatedly failed to reach a final agreement on gas supplies.

"We are continuing the work in the G20 to regulate financial derivative instruments, particularly in the non-exchange markets," said Sergei Storchak, Russian deputy finance minister. "The work is going on and we are preparing regulatory measures. Our objective is to make things less volatile but not regulate prices."

Storchak said the main task of the Russian presidency of the G20 concerns finances, saying the goal of the G20 is to bring the development of financial institutions and financial markets more in line with their real regulatory authority.