(Adds Sefcovic, PIX, detail)
By Vladimir Soldatkin
BRUSSELS, Sept 19 (Reuters) - Ukrainian Energy Minister Oleksiy Orzhel hoped to reach a deal with Moscow on gas transit to Europe during negotiations in Brussels on Thursday while his Russian counterpart Alexander Novak said he was ready for "constructive" talks.
The Russia-Ukraine gas transit agreement expires in January. Ukrainian energy authorities are worried that Moscow could stop gas supplies through Ukraine, leaving some parts of the country without gas in winter.
More than a third of Russia's gas exports to the European Union cross Ukraine, providing Kiev with valuable transit income, and Orzhel said "it would probably be good" if the two sides could reach an agreement on Thursday.
"We're ready for constructive talks," Novak said ahead of the meeting, in which the EU's top energy official, Maros Sefcovic, acts as a moderator.
With animosity between Moscow and Kiev running high, especially since the Kremlin annexed Crimea from Ukraine in 2014 and sided with rebels fighting government troops in the east of the country, Sefcovic held separate meetings with each of the visiting ministers before the trilaterals.
"We welcome the substantial progress on NaftogazUkraine unbundling, as an element important for successful outcome of trilateral talks," Sefcovic said after meeting Orzhel in referring to Ukraine's state energy company. (Reporting by Vladimir Soldatkin; writing by Tom Balmforth; Editing by Dale Hudson and David Evans)