"In the middle of December, there was a trend of a reduction of gas offtake which confirms that Ukraine is facing serious difficulties with (future) gas payments," Miller said. MOSCOW, Dec 25 (Reuters) - Russia's gas export monopoly Gazprom said on Dec. 25 Ukraine was facing difficulties with payments for its gas, news agencies quoted Gazprom's Chief Executive Alexei Miller as saying.

A dispute between the two countries led to gas supplies to Europe being cut off in January 2009, leaving millions of homes without heat at the height of winter and damaging the industry.

"We assess the situation with payments for Russian natural gas deliveries in December as very alarming," RIA news agency quoted Miller as saying.

"In the middle of December, there was a trend of a reduction of gas offtake which confirms that Ukraine is facing serious difficulties with (future) gas payments," Miller said.

Russia and Ukraine agreed this week to postpone the date by which Kiev must pay for December gas supplies due to the New Year holidays.

Europe receives a fifth of its gas from Russia via Ukraine.