Gazprom has announced a massive increase in the price Ukraine must pay for gas.

Russia’s natural gas producer wants over than 40 percent more, stepping up economic pressure on Kiev in its political standoff with Moscow.

Gazprom’s Chief Executive Officer, Alexei Miller, says the rise is needed because Ukraine’s debt for unpaid gas bills now stands at 1.9 billion euros.

The firm claims the hike is in line with earlier agreements as transportation tariffs have increased.

Russian President Vladimir Putin agreed in December to a discount for Ukraine after its abrupt decision not to sign a trade agreement with the EU and rebuild economic ties with Moscow instead.