The Defence Ministry in Moscow said 498 Russian soldiers have been killed and 1,597 injured in fighting in Ukraine, marking the first time casualty figures have been released by the government since the Kremlin's invasion began a week ago.
On the Ukrainian side, there have so far been 2,870 deaths and about 3,700 wounded, said Igor Konashenkov, spokesman for the Russian Defence Ministry.
Ukrainian President Volodymyr Zelenksy later said 9,000 Russians had been killed, in a video message early Thursday.
The Ukrainian Defence Ministry had previously reported that around 6,000 Russian soldiers had been killed since the war began.
These figures cannot be independently verified, and Ukraine has not given any current information about casualties in its own ranks.
Zelensky said the Russian troops would only get one thing from the Ukrainians: "Resistance so fierce that they will forever remember that we will not give up what is ours."
Second round of talks
Both sides had earlier said they were open to holding a second round of talks.
The head of the Russian delegation, Vladimir Medinsky, told Russia's Ria Novosti agency late Wednesday that a possible ceasefire would be a topic at the negotiations planned for Thursday morning.
He said both sides had agreed on the Brest region in western Belarus as the venue for the talks and that the Russian military will set up a "security corridor" to allow the Ukrainian delegation's passage.
The Ukrainian side confirmed it agreed to hold discussions but has said little else, including the time and place.
Ukraine's Foreign Ministry, however, urged Russia to declare a ceasefire in the hard-hit eastern regions of Kharkiv and Sumy to allow civilians to reach safety.
The first negotiations on Monday at the Belarusian-Ukrainian border brought no tangible results.
Russian army controls Kherson
Russian attacks continued to pummel Ukraine on Wednesday, and several explosions were registered in Kiev early Thursday, triggering air raid sirens.
Earlier the Ukrainian capital, a blast at the southern end of the city's main station caused slight damage but did not halt services, the state-owned railway company said.
The picture on the ground remained complicated as both sides reported military successes.
The Russian military said it had gained full control of the southern Ukrainian city of Kherson, which had been under siege for days. That would make it the fist major city to fall since the war began.
A Russian win there would also make it harder for Ukrainian forces to shift personnel and supplies between the east and the west.
Ukraine denied Russia's claim of control and said the city was still being contested.
The eastern Ukrainian city of Kharkiv, with its population of over a million, also experienced renewed attacks.
According to Ukrainian military reports, the settlement of Makariv, in the west of the Kiev region, was retaken. Ukrainian soldiers also reported success near Horlivka, in the Donbass region.
The information could not be independently verified.
2,000 civilians dead
Overall, at least 2,000 civilians have died since Russia invaded, the Ukrainian state emergency service said.
Russia's invasion has prompted a global outcry, with Russian planes now banned from much of European and American airspace, Russians barred from many international events and sanctions imposed to severely limit Russian access to the international banking system.
The US on Wednesday announced further sanctions on Russia and the introduction of strict controls on the export of high-tech products to its ally Belarus.
The UN General Assembly wrapped up an emergency meeting - only the 11th of its kind at the UN in more than 70 years - with a large majority member states voting in favour of a resolution denouncing the Russian attack.
US Secretary of State Antony Blinken, who was to set off for a six-nation European tour on Thursday, said a diplomatic path to ending the war was still open, if Russia pulled back forces.
"We of course remain open to pursuing any reasonable path, but it's very hard to see any path when the bombs are dropping, the planes are flying the tanks are rolling," Blinken said at the US State Department.
Meanwhile, Sweden said four Russian fighter jets briefly violated its airspace east of the Baltic island of Gotland on Wednesday.
Fighter jets from the Swedish Air Force documented the incident, which involved two Russian SU-27 and two SU-24 jets. "This is an unprofessional and irresponsible action on the part of Russia," said Air Force Chief Carl-Johan Edström.