OAO Gazprom's proposed purchase of E.ON AG's natural gas assets in Hungary could deter competition in Hungary's energy market, a government official said to daily Magyar Hírlap."This could be a further step toward monopoly," István Pataki, deputy chairman of the Hungarian Energy Office said by telephone today. "Gazprom also being the largest gas supplier may be unfavorable from the competition point of view." E.ON, which received EU approval for buying MOL Rt's gas wholesale and storage units in December, offered to swap some Hungarian assets for a stake in Gazprom's Yuzhno-Russkoye field. The Russian company's expansion into Hungary runs counter to efforts by Hungary to diversify its gas supplies after Russian deliveries of the fuel were cut 20-25% earlier this year due to a cold snap.