Kremlin rebukes Biden for 'war criminal' talk

US President Joe Biden referred to Russian President Vladimir Putin as a "war criminal" on Wednesday, prompting a rebuke from the Kremlin.

"We believe such rhetoric to be unacceptable and unforgivable on the part of the head of a state, whose bombs have killed hundreds of thousands of people around the world," said Putin's spokesman Dmitry Peskov, according to news agencies TASS and Ria Novosti.

Biden made the remark to reporters while he was explaining that the United States was offering an additional $800 million in security assistance to Ukraine to fight Russia, with the new package including drones and anti-armor systems. The US has pledged a total of $13.6 billion in overall aid to Ukraine.

He was asked at the White House by a reporter if he considered Russia's president a war criminal. Initially, Biden responded, "No," but then he asked the journalist to clarify the question and said: "Oh, I think he is a war criminal."

The remark followed the US Senate unanimously passing a resolution Tuesday calling Putin a war criminal.

White House press secretary Jen Psaki, who has been sanctioned by Russia, said Wednesday that there was a separate legal process run by the State Department to determine war crimes and that was ongoing separately.

The Geneva Conventions ratified by the United Nations define war crimes as willful killing; torture or inhuman treatment, including biological experiments; willfully causing great suffering, or serious injury to body or health; extensive destruction and appropriation of property, not justified by military necessity and carried out unlawfully and wantonly; compelling a prisoner of war or other protected person to serve in the forces of a hostile power; willfully depriving a prisoner of war or other protected person of the rights of fair and regular trial; unlawful deportation or transfer or unlawful confinement, and taking of hostages.

Biden also accused the Russian military of bombing hospitals and apartment buildings, which Moscow has denied.

Putin stressed that Russian forces "are working with modern high-precision weapons", hitting only military targets.

On Wednesday, Putin said he was prepared to discuss neutral status for Ukraine but that the special military operation to "demilitarize and denazify" the country was "going to plan", justified by the need to uphold Russian security.

Putin also gave a televised speech in which he accused the West of trying to divide Russia with lies and criticized "traitors" inside Russia, the BBC reported.

"Of course they will try to bet on the so-called fifth column, on traitors — on those who earn their money here but live over there. Live, not in the geographical sense, but in the sense of their thoughts, their slavish thinking," Putin said.

"Any people, and especially the Russian people, will always be able to distinguish the true patriots from the scum and the traitors, and just to spit them out like a fly that accidentally flew into their mouths," he said.

Ukrainian President Volodymyr Zelensky said negotiations with Russia were becoming "more realistic", and Russia's foreign minister said proposals under discussion were "close to an agreement".

In a speech to the US Congress by video on Wednesday, Zelensky appealed for tougher sanctions on Russia and more weapons to help his country, repeating a request for a no-fly zone over Ukraine, something the West fears would worsen the conflict.

Zelensky last month sent separate letters to Meta Platforms (parent of Facebook and Instagram) CEO Mark Zuckerberg and COO Sheryl Sandberg, asking them to block Russia's media outlets from posting on Facebook in Ukraine, according to a Bloomberg report. He also asked that they cut off Facebook and Instagram in Russia itself. Neither Zuckerberg nor Sandberg responded.

Meta also clarified Monday that users cannot make posts calling for the assassination of Putin or other heads of state. The Silicon Valley social media company also said that a previously reported temporary easing of its hate-speech policy applies only to posts by users in Ukraine making threats to occupying forces and "only in the context of speech regarding the Russian military invasion of Ukraine".

Russia on Friday opened a criminal case against Meta over the policy.

"A criminal case has been initiated ... in connection with illegal calls for murder and violence against citizens of the Russian Federation by employees of the American company Meta, which owns the social networks Facebook and Instagram," Russia's Investigative Committee said.

Reuters contributed to this story.