Oil prices edged higher on Tuesday in thin pre-Christmas trading after Russia’s energy minister said cooperation with OPEC to support the market would continue and as analysts forecast a second weekly decline in U.S. crude inventories. OPEC, Russia and other producers that have linked up to curtail production and support prices will continue their cooperation as long as it is “effective and brings results,” Russian energy minister Alexander Novak said in an interview on Monday Still, OPEC needs to do more to balance out the market on a sustainable basis, Bjornar Tonhaugen, head of oil market research at Rystad Energy said in a note. Crude stocks are, however, expected to have fallen by about 1.8 million barrels last week, a second week of declines, according to a preliminary Reuters poll.