Russia\'s average spot prices for gasoline rose by 1.1-1.7 percent last week despite a high export duty imposed by the government to stabilize the domestic market, Vedomosti daily reported on Tuesday. Gasoline prices are likely to rise soon on the domestic retail market as demand for fuel on the petroleum products exchange is far higher than supply, the paper quoted Pavel Strokov, head of the Kortes analytical company, as saying. \"There are signs of a new deficit spiral on the high-octane gasoline market,\" he said. All Russian refineries producing fuel above Euro-2 standard are working at full capacity and gasoline has not been exported since May due to high export duties but there is still a shortage of fuel on the domestic market, an oil company employee told the paper. The government boosted the gasoline export tariff to a nearly prohibitive 44 percent from May 1 to fight local shortages which started in April in some regions. Russian oil companies had preferred to sell gasoline abroad where prices are higher than in Russia, where the state has capped prices. The Federal Antimonopoly Service has accused large oil firms of price collusion. It has ordered them to bring wholesale fuel prices down in line with market prices and warned that it may launch new investigations into price fixing.