Ukraine war: Russians start leaving Ukraine's Kherson city
Vladimir Saldo said all Russian-appointed departments and ministries would cross the Dnieper river.
Some 50-60,000 civilians would also leave in an "organised, gradual displacement", he said earlier.
Ukraine has called on residents to ignore the Russian move.
The head of Kherson's regional administration said Russia wanted to take civilians hostage and use them as human shields. The transfer or deportation of civilians by an occupying power from occupied territory is considered a war crime.
But Ukrainian officials have questioned whether large numbers of people are actually being evacuated, suggesting that images of a crowd assembled by the river are largely for show.
Serhiy Khlan, an aide to the ousted head of the Kherson region, suggested the "deportations theatre" could be acting as cover for a much bigger Russian move: a complete military evacuation from the west bank of the river.
"I foresee the withdrawal of troops," he said, adding that he expected Russian forces to attempt to destroy the city after leaving.
Russia, he said, was planning to establish a new capital for the Kherson region at Henichesk, close to the Crimean Peninsula, adding that banks and offices related to the occupation of Kherson had already been evacuated.
One Kherson resident told the BBC's World Service that she was not going anywhere until Kherson was liberated by Ukrainian troops: "People are not panicking, nobody wants to be evacuated."
She said that Russian soldiers were now worried how they could survive in the city. "There are plenty of them here; they are dressed as civilians. We can see them - they are different to Kherson people. They walk in groups, their hair is cut short, they are dressed mainly in black."
Ukrainian officials have warned that this might represent the start of a forcible deportation to Russia.
Russian-appointed officials say staff and civilians will leave Kherson city because of Ukraine's offensive.
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