"The government on the whole considers the agreement a step ahead, but there are five to seven aspects of quite a serious nature which will need additional consultations with Gazprom," Oleksandr Shlapak said without elaborating.
The Ukrainian government approved in general earlier on Wednesday the Gazprom-Naftogaz March 13 gas deal, which ended the two countries' dispute over the Ukrainian debt and a new supply scheme, which prompted the Russian gas monopoly to briefly cut supplies to the ex-Soviet country by 50%.
Speaking later on Wednesday about drawbacks in the deal to be discussed with Gazprom, Prime Minister Yulia Tymoshenko said the 'at least 7.5 billion cubic meters of gas' in direct supplies to Ukraine guaranteed to Gazprom should be the upper limit.
The premier said Ukraine's government would also seek to sign a long-term strategic treaty with Russia, setting out price formulas for gas supplies to Ukraine and transits via its territory. She said the countries should sign shipment and transit contracts for periods of at least 5-10 years, rather than every year as is currently the practice.
Naftogaz will resume talks with Gazprom as soon as the government finalizes its proposals, Tymoshenko said.
In the March 13 deal, Gazprom also 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.
However, the price is set to rise considerably next year, as Uzbekistan, Turkmenistan and Kazakhstan announced they would begin exporting their natural gas at European-level prices from 2009.
Russia has been gradually raising prices for natural gas shipped to the former Soviet republics, and is already using market pricing for gas supplies to the Baltic nations.
Pricing disputes between Russia and Ukraine, which transits about 80% of Russia's Europe-bound gas, have raised concerns among European consumers. A bitter New Year price row in 2006 led to a brief cutoff of supplies to Ukraine and a shortfall of shipments in some EU states.
