President Joe Biden said Monday he is "very concerned" by Moscow's crackdown on opposition leader Alexei Navalny and other actions, but said the United States and Russia need to cooperate on nuclear arms control.

Speaking after mass arrests of people demonstrating across Russia this weekend against President Vladimir Putin and the jailing of Navalny, Biden said he was "very concerned."

US President Joe Biden Speaking after mass arrests of people demonstrating across Russia this weekend against President Vladimir Putin and the jailing of opposition leader Alexei Navalny, US President Joe Biden said he was "very concerned" Photo: AFP / JIM WATSON

However, he said that talks on extending the soon-expiring New START nuclear arms treaty also have to be prioritized.

"I find we can both operate in mutual self-interest of our countries as a New START agreement and make it clear to Russia that we are, we are very concerned about their behavior," Biden told reporters at the White House.

Biden also referred to the huge hack of US computer networks, which has been blamed on Russia, and reports that Russia had offered the Taliban bounties to kill US soldiers in Afghanistan.

Protesters march in support of jailed opposition leader Alexei Navalny, who was jailed upon returning to Russia after five months in Germany recovering from a near-fatal poisoning, in downtown Moscow on January 23, 2021 Protesters march in support of jailed opposition leader Alexei Navalny, who was jailed upon returning to Russia after five months in Germany recovering from a near-fatal poisoning, in downtown Moscow on January 23, 2021 Photo: AFP / Kirill KUDRYAVTSEV

"I have asked the agencies in question to do a thorough read for me on every one of those issues, to update me precisely where they are, and I will not hesitate to raise those issues with the Russians," he said.

Earlier, White House Press Secretary Jen Psaki would not specify what Biden's response might be, saying only his options were open.

"As has always been the case, the president reserves the right to respond in the time and manner of his choosing. And I'm not going to take options off the table from here," she told reporters.

On Saturday, the State Department condemned "harsh tactics" used to confront nationwide demonstrations in support of Navalny.

On the issue of Paul Whelan, a US citizen convicted on spying charges in Russia last year and sentenced to 16 years of hard labor, Psaki indicated that the Biden administration would take a different tack to the previous Donald Trump administration.

"Certainly we don't plan to follow the same pattern of the last administration," she said.