Ukraine's southern Kherson region will start using the Russian rouble from May 1, an official from a pro-Russian committee which styles itself as the region's "military-civil administration" told Russian news agency RIA.
The official, Kirill Stremousov, said that the transition to the Russian rouble will take up to four months, during which time it will circulate alongside Ukraine's official currency - the hryvnia, RIA reported.
On Tuesday, Russia said it had gained full control of the Kherson region, which is strategically important as it provides part of the land link between the Crimea peninsula and Russian-backed separatist areas in the east.
Local authorities in Ukraine say Russia has appointed its own mayor in the city of Kherson and taken over the regional headquarters, the first big urban center to be seized after Russia sent tens of thousands of troops into Ukraine on Feb. 24.
(Reporting by Reuters; editing by Guy Faulconbridge)