President Vladimir Putin’s spokesman said Wednesday that Russia was increasingly concerned about Ukraine’s growing debt on its gas payments and needed an explanation about Kiev’s future policies in the face of pro-EU protests.

President Vladimir Putin's spokesman said Wednesday that Russia was increasingly concerned about Ukraine's growing debt on its gas payments and needed an explanation about Kiev's future policies in the face of pro-EU protests.

Kremlin spokesman Dmitry Peskov said Putin would keep to his pledge to provide Ukraine with a $15-billion bailout package that also slashes the price for Russian gas shipments as long as Kiev kept the commitments it had previously made to Moscow.

"In case of the basic fulfilment of existing documents, no one will have any grounds to review anything," Peskov told Kommersant FM radio.

But he added that "we are concerned about the growing debt for gas deliveries."

Russia's natural gas giant Gazprom said this week that Ukraine's state energy company owed $3.29 billion in payments for 2013 and January of this year.

"Gazprom has already said that the debt is growing, and growing very fast. We hope that our Ukrainian partners will implement all the points of our existing agreement," Peskov stressed.

Putin told EU leaders in Brussels last week that Russia would honour the terms of the Ukrainian bailout no matter who came to head the Kiev government next.

Ukraine's pro-Russian Prime Minister Mykola Azarov resigned last week in the face of two months of pro-EU protests on the streets of Kiev.

But Russian officials have since suggested that they will wait for the new Ukrainian cabinet chief to clarify his economic position before releasing the remaining $12 billion of the aid package and keeping to the terms of the gas rebate deal.

Those concerns about Ukraine's future political and economic policies were echoed by Putin's spokesman on Wednesday.

"Of course, it will take some time before the new Ukrainian head of government is able to explain to Moscow how much he intends to keep to the previously-declared (political) course," said Peskov.

"We simply need a basic understanding of what is going to happen to these funds," the spokesman said in reference to the bailout payments.