At a meeting with his prime minister and the head of state oil and gas company Naftogaz, President Viktor Yushchenko said that although he broadly supported the deal, it had altered a key instruction he earlier issued.
The agreement guarantees Gazprom minimum annual gas sales in Ukraine of 7.5 billion cubic meters, rather than setting this figure as an upper limit, as Yushchenko had ordered, press secretary Irina Vannikova said.
"This detail needs to be clarified," she said.
Premier Yulia Tymoshenko and Naftogaz CEO Oleh Dubyna met with the president to discuss details of the agreement reached on Thursday between Gazprom and Naftogaz to end their long-running gas dispute.
Under the deal, Gazprom committed itself to supplying Ukraine with at least 49.8 billion cu m of Central Asian gas at $179.5 per 1,000 cu m from March until December 2008.
Gazprom and Naftogaz also axed intermediaries from the natural gas supply chain.
