Russia said on Friday that Ukrainian forces had killed at least four people and wounded 13 more in a missile attack on civilians evacuating from the Russian-controlled city of Kherson.
A Ukrainian official acknowledged an attack, but said it occurred after a civilian curfew.
Russian-installed authorities in the southern Ukrainian region which Moscow proclaimed as annexed last month are evacuating around 50,000-60,000 people across the Dnipro River ahead of an expected Ukrainian counteroffensive.
Russia's investigative committee said that Ukrainian forces deliberately attacked a civilian column as it was crossing the Dnipro river from Kherson.
"It has been established that the civilian column was crossing from Kherson to the other side of the river when Ukrainian nationalists deliberately struck with American MLRS HIMARS with cluster munitions," it said.
It said two journalists were among the dead. Russian-installed officials said some children were among the wounded.
The deputy chair of Ukraine's regional council in Kherson - who is on Kyiv-held territory - said Ukrainian forces carried out a strike on a barge at around 2300 local time, but denied there were civilians on it.
The official, Yuriy Sobolevskyi, said the strike was conducted after the civilian curfew and cited reports saying some of the people evacuating from the west bank of the Dnipro were part of Russia's security structures.
Russian forces have been driven back by 20-30 km (13-20 miles) in the last few weeks, and risk being pinned against the western bank of the Dnipro as Ukraine wages a counteroffensive in the region.
(Reporting by Reuters; Editing by Christian Schmollinger, Guy Faulconbridge and Philippa Fletcher)
