KIEV, Aug. 25 - Ukraine said Tuesday that the leaders of Germany and France had agreed to back "firm" steps against Russia should pro-Moscow rebels hold disputed elections in the ex-Soviet state's separatist east.

A top aide to President Petro Poroshenko said German Chancellor Angela Merkel and French President Francois Hollande had agreed at trilateral talks in Berlin on Monday to a set of "red lines" Russia must not cross, AFP reported.

"European leaders agreed on a set 'red lines' whose violation by Russia would prompt a firm EU response," deputy administration chief Kostyantyn Yeliseyev told reporters.