The proposal made by Gazprom involves making a prepayment for three billion cubic meters (bcm) under the 2009 gas contract, which is not agreeable to Ukraine, Naftogaz CEO Andriy Kobolev said on Channel 5 on Thursday, June 30, evening.

"The existing contract is built in such a way that to begin withdrawing gas we must at once make a prepayment for a large volume... That is at least three billion cubic meters which Ukraine does not need at present for the month, this is an overstated volume, and it is a serious problem of this contract," he said.

Nor does the current version of the contract stipulate a Gazprom guarantee to strictly stick to the gas supply schedule and destinations, Kobolev said.

"What are the guarantees that all of the gas will be supplied, that it will be supplied precisely to those points of withdrawal, which are controlled by the Ukrainian state and that we can verify? In other words, there are many unsettled issues," Kobolev said.

So Naftogaz sent Gazprom a letter proposing to sign an addendum to the 2009 gas contract, which would stipulate details of possible shipments in the third quarter of this year.