KIEV, May 18 – The signing of a memorandum between Russia's Gazprom and Italy's Eni about the increase in capacity of the South Stream pipeline from 31 to 63 billion cubic meters a year is a political and not an economic decision, Ukrainian presidential envoy for energy security Bohdan Sokolovsky said.

"I cannot say that this is a friendly step towards Ukraine and I believe that political motives are behind this decision, in the first place, as increasing the capacity of Ukraine's gas transportation system is more economically beneficial and according to the preliminary estimate will cost half as much," the envoy said.