President Barack Obama said Friday he had confronted Vladimir Putin in person over allegations of Russian hacking when they met ahead of the US election, telling him to "cut it out."

Alerted over the summer to Russian hacking of the Democratic Party, Obama told a news conference his chief concern was to ensure the cyber attacks did not escalate and hamper the vote counting process.

"In early September when I saw President Putin in China, I felt that the most effective way to ensure that that didn't happen was to talk to him directly and tell him to cut it out and there were going to be serious consequences if he didn't," Obama said.