Kyiv said Russia had more than 1,000 soldiers killed and wounded in a 24-hour period on the frontline.
The losses for Putin’s troops include 48 artillery systems and 23 armoured combat vehicles, said the General Staff of the Armed Forces of Ukraine.
The estimate comes after British officials said Russia has lost more than 70,000 troops in the past two months.
In a briefing on Friday, the Ministry of Defence added that the heavy losses were likely to continue as Putin’s forces seek to make frontline gains.
“The average daily Russian casualties (killed and wounded) in Ukraine, throughout May and June 2024, increased to conflict highs of 1,262 and 1,163 respectively,” the MoD wrote.
“In total, Russia likely lost (killed and wounded) in excess of 70,000 personnel over the past two months.”
Separately, shelling of Ukraine's Kherson region killed two people on Saturday, local officials said.
Two others were wounded in the attack close to the regional capital, said Oleksandr Prokudin, governor of the partly occupied Kherson region.
In Russia's south-western Rostov region, an oil depot in the Tsimlyansky District, deep inside the region, was set ablaze in the early hours of Saturday following a Ukrainian drone attack - the latest long-range strike by Kyiv's forces on a border region.
Ukraine has in recent months stepped up aerial assaults on Russian soil, targeting refineries and oil terminals in an effort to slow down the Kremlin's war machine.
It comes after Ukraine’s Volodymyr Zelensky said he can "forget" US President Joe Biden's gaffe in which he referred to him by Russian President Vladimir Putin's name.
Mr Biden accidentally introduced the Ukrainian leader as “President Putin” at the Nato conference, in a gaffe which intensified concerns about his mental fitness.
He quickly corrected himself, with Mr Zelensky responding: “I am better.”
Speaking on a trip to Ireland on Saturday, Mr Zelensky said: “It's a mistake. I think United States gave a lot of support for Ukrainians. We can forget some mistakes, I think so."
He was embraced by Irish premier Simon Harris as he descended from his plane in Shannon airport.
Asked by reporters for his message to Ireland, Mr Zelensky expressed his gratitude to the country, saying “you were with us from the very beginning of the Russian invasion."
