Ukrainian Prime Minister Arseny Yatsenyuk urged Russia on Tuesday not to use natural gas as a "weapon" against his country, and accused Moscow of seizing tens
of billions of dollars' worth of its assets and energy resources
Russian energy giant Gazprom earlier demanded a $1.66 billion pre-payment from Kiev for June gas deliveries, saying Ukraine had only half its requirements in storage to ensure a trouble-free winter.
"We are ready for a market-based approach and Russia is to stop using natural gas as another, or a new type of Russian weapon," Yatsenyuk told a news conference with European Commission President Jose Manuel Barroso in Brussels.
Ukraine wants to change the conditions of a 2009 contract that locked Kyiv into buying a set volume of gas, whether it needs it or not, at $485 per 1,000 cubic meters - the highest price paid by any client in Europe.
Moscow dropped the price to $268.5 after then-President Viktor Yanukovych turned his back on a trade and association agreement with the European Union last year, but reinstated the original price after he was ousted in February.
Ukraine pushes back
Kyiv has so far refused to pay the higher price, saying gas is being used as a political tool by Moscow to punish Ukraine's new leaders for moving closer to the EU.
Yatsenyuk said Ukraine was ready to pay its arrears for Russian gas within 10 days if state-controlled Gazprom agreed to sell it at $268 per 1,000 cubic meters.
But he repeated a threat to take Gazprom to an arbitration court in Stockholm if the two sides failed to agree on a price by May 28, and said he was making a "final call" to Russia to sit down and negotiate a solution to the gas dispute.
Yatsenyuk accused Russia of seizing Ukrainian property worth tens or even hundreds of billions of dollars, including Crimean gas company Chernomorneftegaz, when it annexed the region in March.
"They have stolen more than 2 billion cubic meters of Ukrainian natural gas. They've stolen our fields, they have stolen our companies, they have stolen our onshore and offshore drills. We will see Russia in court too," he said.
US, EU Sanctions
The United States and its European allies, in condemning Russian intervention in Ukraine, have imposed visa bans and asset freezes on a long list of Russian corporate leaders and advisers close to President Vladmir Putin.
Now, Moscow says it will bar the use of Russian-made rocket engines on U.S. military satellite launches. The U.S. has a two-year supply of the engines, but the ban could eventually force it to turn to other, more costly launch vehicles.
Russia also said it has rejected a bid by the U.S. to extend use of the 15-nation International Space Station beyond the previous target of 2020 to 2024.