After an accident on the Druzhba pipeline in western Russia in July, crude supplies to Mazeikiu Nafta were interrupted, and have not been fully resumed.
"If supplies of Russian crude oil by pipeline to MN are not resumed within the next few weeks, this could lead one to conclude that political rather than technical reasons are to blame for the supply disruption, as the Lithuanian refinery was recently acquired by Polish PKN and not by a Russian oil company," Fitch said.
Bankrupt Russian oil company Yukos had previously held a controlling stake in the Baltic region's largest refinery, which the Lithuanian government recently bought, before selling to the Polish company, rejecting bids from leading Russian oil producers.
The agency also said that oil refineries in Central Europe were vulnerable to supply risks due to their dependence on Russian crude.
"While recent supply problems due to a leak in the northern branch of the Druzhba pipeline were only experienced by Lithuanian refinery Mazeikiu Nafta AB... most other refineries in the CE region are dependent on pipeline supply from Russia."
Refineries in the region do have access to alternative supplies of crude, but interruptions to supplies from Russia would severely hit their profits, Fitch said.
"CE refineries' dependence on Russian crude is a combination of historical reasons and refinery location on the pipeline from Russia. This is also driven by increasing price advantage of Russian crude oil, which is sold at a discount to Brent oil (as much as USD5/bbl in Q206)," the agency said.
"It is Fitch's view that a mixture of political and economic reasons are behind the interruptions of Russian crude oil and gas supply to Central Europe experienced in the past two years... However, Fitch views that intentional long-term supply disruption to CE refineries is unlikely given that Russian oil companies remain interested in exporting crude oil to this region, given its price advantage over domestic sales and difficulties to redirect such significant amounts of crude oil into other export routes."