Lithuania has initiated a 1.5 billion euros ($1.9 billion) lawsuit against Gazprom with the Stockholm Arbitration Tribunal, for what is says were overpriced gas supplies, the Lithuanian Energy Ministry said on Wednesday.

Lithuania claims it has overpaid 5 billion litas (1.448 billion euros) to Gazprom for gas supplied to under its existing contract.

Under the terms of public privatization and the 2004 agreement on the privatization of Lithuania's biggest energy company, Lietuvos dujos, Gazprom undertook to supply natural gas to Lithuania at fair prices and in accordance with the gas price formula indicated at that time in the gas supply contract signed between the two companies.

“In the period between 2004 and 2012, Gazprom’s price for gas supplies increased significantly due to changes in the gas price formula that were made in violation of the terms of the agreement on [the company’s] privatization,” the ministry said.

“These changes in the gas price formulas were also endorsed by Lietuvos dujos management board members who had been appointed by Gazprom and who possibly acted in the interests of Gazprom rather than Lietuvos dujos by voting for changes in the gas supply contract.”

Lithuanian Prime Minister Andrius Kubilius has said Lithuania tried to persuade Gazprom to settle the gas price dispute without taking the matter to the court but to no avail.

Gazprom owns a 37.1 percent stake in Lietuvos dujos, while Germany's E.On Ruhrgas holds 38.9 percent, the Lithuanian State Property Fund has 17.7 percent and other individuals and legal entities own 6.3 percent.