Moscow, Russia - The Russian government is following the publication of what appear to be secret US documents on the war in Ukraine with interest, an official said, but added that he would not comment on whether it was behind the leaks.

"The leaks are reasonably interesting," Kremlin spokesperson Dmitry Peskov said on Monday. "Everyone is studying, analyzing and discussing them widely."

Reports on the contents of the documents published have come thick and fast. The material appears to contain information from US intelligence services on Ukrainian warfare.

Asked about possible involvement of Russian agencies in the publication, the Kremlin spokesman said he could not comment.

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"We all know that this is again about this tendency to blame Russia for everything, always and everywhere, and to pin everything on Russia," Peskov said.

This blaming is a "widespread disease," which is why there is nothing to comment on, he said.

After the first leaks were reported on Friday, Peskov said the documents showed how deeply the United States and NATO states were involved in the war in Ukraine.

There were also reports that the US had spied on Ukrainian President Volodymyr Zelensky. "This cannot be ruled out," Peskov said.

There have been previous reports about the US spying on various heads of state and government, especially in European capitals, which had led to scandals, he said.

In 2013, for example, the then German chancellor Angela Merkel was outraged after it was reported that the US National Security Agency had tapped her mobile phone, Peskov said.