MOSCOW, April 10 (Reuters) - President Vladimir Putin has informed several European leaders about the "critical situation" over Ukraine's natural gas debt and about a possible impact on the transit of gas to Europe, Russian news agencies said on Thursday.
Putin expressed "extreme concern about the situation surrounding Ukraine's gas debts and ... supplies of gas to the European Union," state-run RIA cited Putin's spokesman, Dmitry Peskov, as saying.
State-controlled gas producer Gazprom stopped pumping gas to Ukraine during price disputes in the winters of 2005-2006 and 2008-2009, leading to reduced supplies in European countries that receive Russian gas via pipelines that cross Ukraine.
Gazprom says Ukraine owes $2.2 billion for gas supplies and missed the deadline for paying for its March supplies.
Writing by Steve Gutterman, Editing by Timothy Heritage