Kremlin Spokesman Dmitry Peskov said on Tuesday that personal attacks against Russian President Vladimir Putin by US President Joe Biden are unworthy of the US leader.

This came following Biden's statements on Monday saying that he is seeking additional evidence collection for a possible war crimes trial against Putin after photos from Bucha emerged seeming to depict dead civilians, which Moscow has described as being a heinous provocation.

"As for new sanctions, we know that they are possible. It is unlikely that Americans will abandon their favorite practice. Personal insults to the Russian president continue, and this is bad. We consider this unacceptable and unworthy of the president of the United States," Peskov told reporters.

Russia not to rush transition to payment for gas exports in rubles - Kremlin

Russia will not be hasty in its transition to receiving payments for exports in the Russian national currency after the country's previous decision to make "unfriendly" countries pay for gas in rubles, the Russian Presidential Spokesperson said on Tuesday.

"Obviously, there should not be any hasty moves. There should be a thoroughly thought-out, systematic, meticulously coordinated work. You cannot act it any other way," Peskov told reporters when they asked whether they will act in that direction.

"This is a very staged, very careful movement, which takes into account those financial and economic realities that exist in the global markets," he added.

Last week, Russian President Vladimir Putin signed a decree stipulating that all pipeline gas contracts with companies registered in a country that has imposed sanctions on Russia must be settled in rubles.

Putin-Zelensky meeting possible after sides agree on treaty

In another context, Kremlin Spokesperson Dmitry Peskov said that Russia does not oppose the possibility of a Russia-Ukraine meeting after the two agree on a treaty.

"Nothing has changed for us. We do not reject the possibility of a meeting for our president. But we repeat once again that such a meeting is possible only after the text of the document is agreed," Peskov told reporters.

Peskov was asked about the possibility of Russia-Ukraine negotiations being under threat, and he said that Moscow still prefers not to share information about the process, although Russia's Foreign Minister Sergey Lavrov said the West intends to sabotage Moscow-Kiev talks, which made some progress during an Istanbul summit, by instilling fear about the situation in Bucha.