May 27 (Reuters) - Ukraine's state gas company Naftogaz said on Friday it had launched a pre-arbitration procedure against its Russian counterpart Gazprom, claiming the latter underpaid contractually agreed gas transit fees.

"There is some time during which we should try to resolve the issue before arbitration, if we do not resolve it - (we will begin) new arbitration," Naftogaz CEO Yuri Vitrenko told the Interfax Ukraine news agency on Friday. (Reporting by Natalia Zinets; Writing by Max Hunder; Editing by Jan Harvey)