* Novak tells Die Presse gas supplies to Europe are reliable
* Denies Russia playing games with gas exports
* Sees no reasons for oil price to fall below $90 (Adds quotes and background)
VIENNA, Sept 18 (Reuters) - Russia will not curb gas exports to Europe this winter to prevent countries from re-exporting supplies to Ukraine, Energy Minister Alexander Novak told an Austrian newspaper.
"That is ruled out," he told Die Presse when asked in an interview printed on Thursday whether Moscow would limit gas exports to curb supplies to Ukraine, whose deliveries from Russia have been cut off since mid-June in a row over prices.
Novak said he expected the oil price to firm to around $100 a barrel by the end of the year, adding it was "no tragedy" the price was below that level now and he saw no objective reasons for it to fall below $90.
An oil price drop since July had to do with an economic slowdown and speculative factors as well as increased output in the United States thanks to shale oil exploitation, he said.
Novak saw Russian oil exports falling 4 to 4.5 percent this year as more crude is processed domestically, but said more oil would be available for export once refineries were modernised.
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.
Slovakia, Poland, Romania and Austria have reported slight falls in shipments in recent days from Russia, which is embroiled in a row with the European Union over Ukraine.
Novak denied Russia was "playing games" with gas exports.
"More (gas) was ordered than normal in recent days and Gazprom did not fully cover the higher demand," he was quoted as saying, adding Gazprom had also filled up storage in Russia.
Novak said it was hard to tell on prospects for Russia, Ukraine and the EU to strike a deal on restoring gas supply to Ukraine, noting the situation was more difficult than early this year.
"We hope reason prevails and there is a deal," he said.
Asked if Russia could turn off gas bound for western Europe that transits Ukraine should Kiev tap into this flow, he said: "This is not an issue for Gazprom. We want to supply Europe as contractually agreed."
Pressed on what would happen should Ukraine divert transit supplies, he said: "Then the question is how much comes out of the pipelines in Europe beyond Ukraine. On very cold days all the gas could be tapped and Europe would be without gas." (Reporting by Michael Shields and Shadia Nasralla,; Editing by Mark Potter and Michael Urquhart)