Ukrainian minister of economics Arsenii Yazenuk thinks that Russia should guarantee Ukraine natural gas supplies. "There are several variants for Russia to guarantee gas supplies` obligations in front of Ukraine", - said the minister talking about the necessity of intergovernmental mutual protocol in gas sphere. By his words, first variant is a financial guarantee of large bank. "Russia can present guarantee of international bank and if gas is not supplied in full amount this bank-guarantor will pay out the certain sum", - said the minister. The second variant is the guarantee of Russian Federation. "Gazprom" may conclude the treaty, which provides joint responsibility of affiliated company "RosUkrEnergo" and "Gazprom", - explained Yazenuk. The third variant is a commodity guarantee in the form of at least 3-month gas storage in Ukrainian depots. "In case of "RosUkeEnergo" obligations` failure, this gas will be used by Ukraine", - said the minister.