(Adds comment by military expert paragraph 4, reports from eastern Ukraine, paragraphs 14-16)
By Tom Balmforth and Yuliia Dysa
KYIV, Nov 15 (Reuters) - Ukrainian troops have crossed the vast River Dnipro into occupied areas of Kherson region and are operating in small groups, Russia conceded on Wednesday, saying it had dispatched more troops to stop them.
Ukraine said on Tuesday it had secured a foothold on the eastern bank of the Dnipro "against all odds", a potentially major setback for Russian occupation forces in the south where Kyiv is trying to open a new line of attack.
A Ukrainian military spokesperson added on Wednesday that Ukrainian troops were trying to push Russian forces back from the eastern bank of the river, a formidable natural barrier.
Military expert Oleksandr Kovalenko told media outlet RBK Ukraine that the growing area of contested control on the eastern bank "significantly reduces the mobility and capability of the Russian occupiers".
Vladimir Saldo, the Russian-installed governor of the part of Kherson region under Moscow's control, noted that Ukrainian forces had crossed the river, but were taking heavy losses.
Ukrainian forces, he said in a statement, were operating in small groups spread over an area from a railway bridge to the village of Krynky, a distance of around 20 km (12 miles).
"Our additional forces have now been brought in. The enemy is trapped in (the settlement of) Krynky and a fiery hell has been arranged for him: bombs, rockets, heavy flamethrower systems, artillery shells and drones," said Saldo.
Citing information from Russia's "Dnepr" military grouping, he said Ukrainian forces were pinned down in basements in the day and predicted the Ukrainian assault would be thwarted.
The village of Krynky lies close to the Dnipro around 30 km northeast of the city of Kherson, which Ukraine recaptured almost exactly a year ago.
Natalia Humeniuk, spokesperson for Ukraine's southern military command, described the frontline as "fairly fluid" and said Kyiv's forces had been putting pressure on Russian troops.
"The pushback from our side is taking place on a line from 3 to 8 km along the entire bank from the water's edge," she said.
"For now, we will ask for informational silence ... which would allow us to report later on great successes."
Reuters could not verify either side's accounts.
In Ukraine's east, the head of the military administration in Avdiivka said the Ukrainian-controlled eastern town was "being wiped out" by a month of unrelenting Russian attacks.