Water levels on rivers in Russia and Kazakhstan continued to rise and flood whole villages and cities on Wednesday, with more than 100,000 people evacuated and the Kremlin warning a "very, very tense" situation was expected to worsen.
Fast-melting snow and ice has caused rivers in Russia's southern Urals, western Siberia as well as northern Kazakhstan to reach unprecedented heights, threatening major cities.
Moscow and Astana have been battling the rising rivers for more than five days, with both declaring a state of emergency and saying the floods were the worst in decades.
"The situation is very, very tense," Kremlin spokesman Dmitry Peskov said.
"The water is continuing to rise. Large (amounts of) water are coming to new regions."
He said President Vladimir Putin thus far had no plans to visit the flood zone, saying he was being briefed all the time.
Neighbouring Kazakhstan on Wednesday said that it had evacuated "96,272 people" since the start of the floods -- a figure 10,000 higher than the day before.
Russia said it had evacuated more than 7,700 people, mostly from the worst-hit Orenburg region.
The Ural river had already almost entirely flooded the city of Orsk and had now reached the streets of the regional capital Orenburg.
Officials in the city of 550,000 people said water levels had risen 81 centimetres over the last 24 hours.
The city had not seen such floods since at least 1947, local officials said, calling the rising water "completely unprecedented".
The Ural river depth in Orenburg stood at 996 centimetres on Wednesday morning, well above the "critical level" of 930 centimetres.
"According to expert forecasts, today it will rise again by another 30-70 centimetres," the city administration warned on Telegram.
It called on all residents in potential flood areas to "leave immediately".
In Orsk, rescuers published images of them travelling through flooded streets rescuing kittens from roofs.
Floods are also expected to worsen in the western Siberian city of Kurgan, near the Kazakh border and home to some 300,000 people where the Tobol river has also been swelling.
Local emergency services published images of locals and workers putting bags of sand on the river banks as sirens rang out across the city.
Authorities said the river had risen by 23 centimetres in a day.
Russia's emergency minister Alexander Kurenko was visiting the neighbouring Tyumen region, also affected by the floods.
He said the situation was more "stable" there but instructed officials to warn locals of rising water "on time".
Over the border in Kazakhstan, authorities said 24,000 people were involved in "round-the-clock" rescue and clearance operations, including pumping away water, laying barriers and carrying out "blast work" to prevent "ice jams".
The northern city of Petropavlovsk braced for the worst of the floods, where a surge of the Ishim river was expected to arrive over the next 48 hours.
"A huge flow of water is moving towards Petropavlovsk. Once again, I emphasise: huge," state media quoted regional head Gauez Nurmukhambetov as saying.
Kazakh president Kassym-Jomart Tokayev had called the floods one of the worst natural disaster to hit the huge Central Asian country in decades.
Putin and Tokayev on Tuesday held a phone call, pledging to cooperate on battling the floods.
The Russian opposition criticised Putin for not visiting the affected areas.
Rare protests erupted in flooded Orsk this week over compensation issues and the government's response to the floods.
