Russia is to begin oil production from the extensive Shtokmann gas fields in the Barents Sea three years later than planned, dpa cited the companies involved in the project in Zurich as saying today. French energy company Total, together with Russian gas monopolist Gazprom and oil company Statoil, blamed the delay on "changes in the market situation," though there are also said to be technical problems. Output of liquefied gas will now begin in 2017, instead of 2014 as previously foreseen. An estimated 3.9 billion cubic metres of gas is thought to be held in the difficult-to-access Arctic Shtokman fields.