Russia\'s private natural gas producers took a hit Monday after the state-controlled giant Gazprom cut the domestic market purchases it makes from them to compensate any shortfall in supplies. Analysts said the decision could eliminate between a quarter and more than half of the monthly gas sales made by independent firms such as Novatek and Lukoil, adding up to nearly half-a-billion dollars in losses for the year. Gazprom stock was flat on the news while Novatek was down five percent in afternoon Moscow trading. A spokesman for the energy giant said Gazprom\'s decision would extend until further notice on grounds of \"currently unstable gas demand on the domestic market.\" He added that the freeze would not cover purchases Gazprom makes from its own subsidiaries or the gas it pumps for the private players to their European clients. Analysts expressed surprise at the move because it seemed to contradict the \"take-or-pay\" principle Gazprom itself dictates to European clients that fail to make the agreed volume of purchases per year. That arrangement -- now being investigated by the European Commission -- requires other countries and their utility companies to pay for the gas they do not actually take from Gazprom because of any dips in demand. \"This is simply nonsense,\" Nomos Bank analyst Denis Borisov told the Vedomosti business daily of the surprise announcement. Russian anti-trust officials meanwhile said they were studying whether to investigate Gazprom for abuse of its position of power on the local market. \"If there is an appeal, we will take a look,\" a Federal Anti-Monopoly Service spokesman told the daily. Analysts said gas demand and Russia was still below levels seen prior to the 2008-2009 financial crisis. Gazprom\'s production is also down more than five percent on the year despite forecasts of an improvement over the 2011 figure.