On March 4, masked security agents raided the headquarters of Naftogaz. Valentyn Zemlyanskiy, spokesman for the Ukrainian state energy company, said the officers demanded to be shown all original documentation relating to the January 19 gas deal between Naftogaz and Russian gas giant Gazprom.
"Clearly, this is discrediting the country, and is making us think about alternative routes for gas deliveries to Europe," Vladimir Putin told a news conference in Moscow after intergovernmental talks with Hungary.
Ukraine's SBU security service, which is overseen by President Viktor Yushchenko, has accused Naftogaz of illegally diverting 6.3 billion cubic meters of natural gas bought from Russia.
The dispute was widely seen as a part of ongoing political wrangling between the president and premier. Following news of the raid, Prime Minister Yulia Tymoshenko said the sole aim of the operation was to "paralyze Naftogaz's activities and destroy the gas distribution system in Ukraine and the system of payments."
The Ukrainian security service said on Thursday it had stopped its investigation into Naftogaz operations after a court ruled the probe was illegal.
Gazprom suspended gas deliveries to Ukraine on January 1 over non-payment, and the sides' failure to reach a new gas deal. A week later, Gazprom accused Ukraine of stealing gas intended for EU consumers and cut off gas deliveries to the European Union via Ukraine, prompting two weeks of gas shortfalls across much of Eastern Europe.
The standoff was resolved after negotiations between Putin and his Ukrainian counterpart Tymoshenko resulted in the signing of a new gas agreement on January 19.