GENEVA, Switzerland - President Joe Biden said on Wednesday that discussions in his first summit with Vladimir Putin were "positive", but warned his Russian counterpart that Washington would not tolerate interference in US democracy.

"The tone of the entire meeting... was good, positive," Biden told reporters after the summit ended.

"There wasn't any strident action taken."

The meeting in an elegant villa overlooking Lake Geneva came at a time when tensions between Washington and Moscow are at their highest in years, and Biden acknowledged there had been a number of disagreements.

But, he stressed, "it was not done in a hyperbolic atmosphere. That is too much of what's been going on."

For Washington, a key complaint is what it characterises as persistent and combative Russian cyber-activity, namely meddling and interference in elections that it says have been carried out either by Russian security services or hackers with links to the Kremlin.

Biden stressed that he had made it clear to Putin "that we will not tolerate attempts to violate our democratic sovereignty or destabilise our democratic elections and we would respond."

Biden also said he had told Putin that "certain critical infrastructure should be off limits to attack -- period -- by cyber or any other means. I gave him a list."

The two leaders agreed to task experts to help build up a common understanding "about what's off limits," and to "follow up on specific cases that originate in other countries, in either of our countries," he said.

"Responsible countries need to take action against criminals who conduct ransomware activities on their territory," he said.

Biden said he had pointed out to Putin that the US also has "significant cyber-capability, and he knows it.

"I think that the last thing he wants now is a Cold War."

Biden also took issue with comments by Putin that seem to justify his crackdown on opposition figures by citing the need to avoid a situation like the storming of the US Capitol in January.

"That's a ridiculous comparison," Biden said.

"It's one thing for literally criminals to break through a cordon, go into the Capitol, kill a police officer and be held accountable, than it is for people objecting, marching on the Capitol and saying you are not allowing me to speak freely."