I think that we will eventually have to deal with the increase in retirement age, said Shatalov in an interview with Echo Moskvy radio on Tuesday.

He said Ukraine and Gazprom had so far failed to finalize a preliminary accord on solving their disagreements. The accord was concluded earlier this month.

Kupriyanov also said Ukraine kept taking Russian gas without Gazprom's authorization.

The report follows a telephone conversation Tuesday between Russian President Vladimir Putin with his Ukrainian counterpart Viktor Yushchenko on the gas dispute.