Armoured personal carriers driven into the eastern Ukrainian city of Slaviansk had been under the control of Ukrainian armed forces earlier on Wednesday, pictures taken by Reuters photographers showed.
A soldier guarding one of six troop carriers now under the control of pro-Russian separatists told Reuters he was a member of Ukraine's 25th paratrooper division from Dnipropetrovsk.
"All the soldiers and the officers are here. We are all boys who won't shoot our own people," said the soldier, whose uniform did not have any identifying markings on it.
"They haven't fed us for three days on our base. They're feeding us here. Who do you think we are going to fight for?," he said.
Armoured personnel carriers marked with the numbers 815, 842 and 847 were among six under Ukrainian control in the centre of Kramatorsk early on Wednesday. They were seen under the control of pro-Russian separatists in the centre of Slaviansk later.
Ukrainian soldiers with the vehicles in Kramatorsk on Wednesday morning identified themselves as members of the 25th paratrooper division.
Some Kramatorsk locals gave tea and food to the Ukrainian soldiers, who appeared dirty and tired and said they had been on "exercises" for four days.
A civilian in Kramatorsk who identified himself as Felix told Reuters he had seen Ukrainian forces give up their vehicles to armed pro-Russian separatists.
A YouTube video showing vehicles with the same markings appeared to show Ukrainian troops peacefully abandoning their vehicles to heavily armed pro-Russian separatists.
A spokesman for the pro-Russian separatists in Slaviansk said the Ukrainians had given up after talks. It was not clear whether there was any threat of force.
Ukraine's defence minister, Myhailo Koval, was travelling to the Donetsk region to establish what is happening, deputy prime minister Vitaly Yarema told journalists in Kiev.
"At the start there was information that the armoured personnel carriers entered the town within the framework of the counter-terrorist operation, but their subsequent fate ..." Yarema said without finishing his sentence.
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