May 1 (Reuters) - Russia probably aims to exert strong political and economic influence on Ukraine's southern region of Kherson in the long term, after ruling out its return to Ukrainian control and initiating a currency switch to the rouble, Britain said.

"Since seizing ... Kherson in early March, Russia has sought to legitimise its control of the city and surrounding areas through installing a pro-Russian administration," the defence ministry said in a Twitter https://twitter.com/DefenceHQ/status/1520635733760950273?s=20&t=iF4whqt3OOJikfbQyg8MXw bulletin on Sunday.

Russia's enduring control of the region and transport links will benefit its ability to sustain advances to the north and west and improve its security control of the nearby Crimea, the update added.

(Reporting by Akriti Sharma in Bengaluru; Editing by Clarence Fernandez)