Russia is introducing advance payment for gas supplies to Ukraine, the Russian Energy Ministry announced in a statement, citing Energy Minister Alexander Novak, the Interfax news agency reports.

According to him, "prepayment for gas supplies will be introduced for Ukraine from June 2014."

According to the statement, the deadline for Ukraine to pay for the gas supplied to it expired on May 7. "Not a single payment has been received from Naftogaz of Ukraine since March this year. Ukraine total debt for gas has reached USD 3.508 billion today," said the ministry.

"In accordance with paragraphs 5.1.5 and 5.8 of the gas supply contract that Gazprom and Naftogaz of Ukraine signed in 2009, failure to fulfill obligations entails automatic transition to prepayment for gas supplies to Ukraine from June 1, 2014,” Novak is quoted as saying.

The Gazprom gas company (Russia) will send a preliminary bill for the June gas delivery to the Naftogaz of Ukraine company by May 16. Actual supplies will be made in volumes corresponding to the amount of payment that Ukraine makes by May 31, the statement explains.