"Starting from July 1, regular bus and train services between Crimea and the regions of Kherson and Zaporizhzhia will be launched for the first time in eight years," Sergei Aksyonov, the pro-Moscow head of Crimea, said on messaging app Telegram.

Members of Russia's National Guard will ensure the safety of travel, he added.

The southern Ukrainian regions of Kherson and Zaporizhzhia have been largely under Russia's control since the first weeks of Moscow's military intervention, and are now being forcefully integrated into Russia's economy.

Russia annexed the Black Sea peninsula of Crimea from Ukraine in 2014.

A growing chorus of Russian and pro-Moscow officials have indicated Moscow intends to remain in the Kherson region and large parts of Zaporizhzhia it controls. Pro-Moscow officials in southern Ukraine have said they are hoping to stage a referendum.

Kirill Stremousov, deputy head of the Russian-backed Kherson administration, confirmed such plans were in the works and local authorities were preparing to stage a "referendum".

"The region of Kherson will make a decision and become part of the Russian Federation," he said on Telegram.