Photo taken on Dec. 17, 2020 in Moscow, Russia shows the live broadcast of Russian President Vladimir Putin speaking during his annual press conference. This year, due to coronavirus-related restrictions, Putin's annual year-end press conference was held online on Thursday. (Xinhua/Bai Xueqi)

Russian President Vladimir Putin on Tuesday submitted a bill to parliament that would extend by five years a key nuclear pact with the US that was set to expire next week.

The New Strategic Arms Reduction Treaty (START), signed in 2010, caps to 1,550 the number of nuclear warheads that can be deployed by Moscow and Washington, who control the world's largest nuclear arsenals.

Putin's draft legislation appeared on the lower house State Duma website Tuesday evening. 

"On January 26, 2021, Russia and the United States reached an agreement on the extension of the treaty," read an explanatory note attached to the bill, published on the lower house State Duma website.

It said that the two sides had "agreed in principle" to extend New START by five years.

The state RIA Novosti news agency cited Leonid Slutsky, foreign affairs chief in the lower house, as saying that the State Duma could consider the bill as early as Wednesday.

The legislation was published after Putin and new US President Joe Biden held their first phone call Tuesday evening.

Following the call, the Kremlin said in a statement that the two leaders had "expressed satisfaction" over the extension talks.

It added that "in the coming days" the two sides will "ensure the further functioning of this important international legal mechanism for the mutual limitation of nuclear missile arsenals."

In its own readout of the call, the White House said Biden and Putin agreed "to have their teams work urgently to complete the extension by February 5," when the nuclear pact is set to expire.

AFP