Fighting between pro- and anti-Russian activists in Odessa left at least 42 people dead last week. Local officials said a gas pipeline running through the city was targeted Sunday during the melee, though reports didn't indicate which side caused the blaze.
Odessa is the latest scene of conflict stemming from political turmoil that erupted in November when Kiev's decisions on moving closer to the European Union forced former President Viktor Yanukovych to flee the country.
The western port city is the starting point of the Odessa-Brody oil pipeline. There were no reports of damage to that pipeline.
Ukraine is a key hub for the European energy sector, hosting the bulk of Russian natural gas supplies through its Soviet-era gas transit network.