PRAGUE, Sept. 29 - It is foolish to expect gas to flow as usual through Ukraine this winter and Europe must brace for disruption along the route that typically carries almost half of Russia's exports to the European Union, a top Czech energy official said on Monday, Reuters reported.

Speaking at the Reuters Eastern European Investment Summit, Czech energy security ambassador Vaclav Bartuska said he doubted a ceasefire between the Ukraine government and Russian-backed separatists would hold through the winter, making it likely that fighting will block deliveries at some point.

"I would say it would be foolish to expect business as usual this winter vis-à-vis transit through Ukraine," said Bartuska, who has served as the EU country's top energy envoy for the past eight years.

"Our baseline scenario for this winter is that there will be no gas through Ukraine, no transit this winter. That is the baseline scenario, that is the expectation."

Russia cut off gas supplies to Ukraine in June because of a row over Ukraine's unpaid gas bill, which followed Moscow's annexation of Crimea and fighting in eastern Ukraine.

Transit through Ukraine has continued, although Gazprom, Russia's top natural gas producer, has significantly decreased deliveries to Europe via Ukraine, electing to supply its customers through alternative routes.

Bartuska said the Czechs had learned their lesson from a pricing dispute in the winter of 2009, when Russians stopped supplies via Ukraine, leaving much of central and southeastern Europe scrambling for gas in freezing temperatures.

New pipeline links have allowed some countries in the region such as the Czech Republic to access western markets as well as the Nord Stream pipeline, which brings gas from Russia to Europe via Germany and bypasses Ukraine, he added.

"For the Czech Republic ... no transit through Ukraine is something we can live with," Bartuska said. "It will be difficult for some countries especially in the south and eastern part of Europe.

"Bulgaria and Hungary from the (EU) member states could be most hit. From the non-members, Moldova and Serbia will probably be most hit."

On Friday, Ukraine and Russia moved closer to a deal that would guarantee Kiev at least 5 billion cubic meters of gas for the next six months if Ukraine made pre-payments.

But on Saturday, Gazprom warned of possible disruptions of Russian gas flows to Europe via Ukraine next winter, due to low volumes of the fuel in Ukrainian gas storage facilities.

Bartuska downplayed the potential pricing deal following European Union-brokered talks, saying what was happening in Ukraine following Russia's annexation of Crimea and fighting in the east was not an energy crisis but a war that will continue to threaten security of supply.

"We have to expect no transit through Ukraine simply because what is happening is no energy crisis, this is real war," Bartuska said. "It only became much worse ever since March." (rt/ez)