Andris Piebalgs said during a joint news conference in Kiev with Ukrainian Prime Minister Yulia Tymoshenko that there was nothing to suggest Ukraine stole Russian gas after Dec. 31, Ukrainian news agency Ukrinform reported Wednesday.
"We have no proof that Ukraine took away gas illegally," Piebalgs said.
Disputes over gas arrears and contracts prompted Russian gas giant Gazprom to halt supplies through Ukraine. The dispute ended Tuesday, and European customers reported gas supplies had resumed following two weeks of disruptions.
The Czech presidency to the European Union said the gas dispute would not be considered settled until Russian gas supplies have "reached the Slovak frontier," Czech Foreign Minister Karel Schwarzenberg said.
The foreign minister said the crisis put renewed focus on European energy diversity as Ukraine and Russia no longer were viewed as reliable energy partners, a news release from the European Parliament said.
"The main lesson learned from this crisis is that Russia and Ukraine aren't reliable suppliers," he said. "Europe must think about alternative sources and pipelines."
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