Hungarian state-owned energy group MVM Zrt. signed a deal to buy German energy giant E.ON AG's (EOAN.XE) Hungarian natural gas units for EUR870 million ($1.11 billion), the companies said in separate statements Thursday.

The transaction includes a natural gas storage and E.ON's local natural gas trade company, and is set to close in the second half of 2013, following approval by authorities, MVM said. The purchase price includes debt, E.ON said.

The final purchase price is dependent on the level of gas reserves at the time of the transaction, MVM said.

Through its long-term gas supply contracts,
Hungary 's long-term natural gas supply agreement with Russia is of the highest importance, given the small European Union member's dependence on Russian gas for heating.