Agreements reached in January to end the gas dispute between Kiev and Moscow should be reviewed as they disadvantage Ukraine, the country's president, Viktor Yushchenko, said Wednesday.
"We must return to the issue of gas relations in a most open manner, on the basis of clear principles," he told reporters in Kiev.
"Neither Ukraine nor Russia can be proud of what was reached in January 2009," he added.
The accords the two countries signed had only generated problems and "do not reinforce stability either in Russia, or Ukraine, or Europe," said Yushchenko.
The accords were "asymmetrical" and disadvantageous for Ukraine because they fixed a minimum amount of gas for Kiev, but did not specify a minimum volume of gas that Russia had to transit to Europe through Ukraine, he explained.
Ukraine is responsible for more than 80% of Russia's gas transit to Europe.
It paid $280 per 1,000 cubic meters for Russian gas in 2009's second quarter - more than the price paid by Germany, he noted.
At the same time, the transit tariffs Russia paid to Kiev remained substantially lower than the standard European price, he added.
"No European company pumps gas through at this price," said Yushchenko.
"Everyone understands that this is unprofitable - the tariffs do not cover the expenses of transport."
In January, a bitter payment dispute between Moscow and Kiev led to a cut-off of Russian gas exports through Ukraine to downstream clients, leaving millions of Europeans without gas in the middle of winter.