MOSCOW, Sept. 17 - Russia's Gazprom said on Wednesday it is unable to meet rising gas demand from Europe while it builds up stockpiles ahead of winter, undermining the ability of Europe to supply Ukraine with gas, Reuters reported.

Slovakia, Poland, Romania and Austria have all reported slight falls in shipments in recent days from Russia, which is embroiled in a row with the European Union over the crisis in Ukraine.

Some countries in eastern Europe send gas to Ukraine, to which Russia stopped gas flows in June over a pricing dispute.