A joint statement issued Tuesday by the Czech Republic, which holds the presidency of the European Union, and the European Commission decried Russian decisions to cut gas supplies to Europe.

"Without prior warning and in clear contradiction with the reassurances given by the highest Russian and Ukrainian authorities to the European Union, gas supplies to some EU member states have been substantially cut," the statement read. "This is completely unacceptable."

Russian energy monopoly Gazprom is seeking $2 billion in debt from Ukraine and a new price mechanism for 2009. Europe receives around 25 percent of its natural gas from Russia. Some 80 percent of that gas travels through Ukrainian pipeline networks.

"The Czech EU presidency and the European Commission demand that gas supplies be immediately restored to the EU and that the two parties resume at once negotiations with a view to a definitive settlement of their bilateral commercial dispute," the statement continued.

The Czech Republic and the European Commission said they intended to negotiate with Ukraine and Russia to seek an immediate resolution to the row.