The White House on Monday urged Russia to "respect" sovereignty and democracy in neighboring Belarus where strongman President Alexander Lukashenko faces mass demonstrations calling for new elections.

"Russia must also respect Belarus' sovereignty and the right of its own people to elect their own leaders freely and fairly," President Donald Trump's press secretary, Kayleigh McEnany, told reporters.

Lukashenko has the backing of Russian President Vladimir Putin, who has raised the possibility of sending military support if Belarus "starts to get out of control."

McEnany said "the massive amount of Belarusians protesting peacefully makes clear that the government can no longer ignore the people's call for democracy."

She added that Washington supports probes into "electoral irregularities, human rights abuses and the government crackdown."

The US demand to Russia follows the European Union's urging on Friday that Moscow refrain from intervening in Belarus.

Lukashenko, who has ruled the ex-Soviet state for 26 years, claimed reelection on August 9 with 80 percent of the vote. He says that the West wanted to see the back of him for its own ends.

Putin, who has been in power for two decades, has said a group of law enforcement officers is ready to move into Belarus if "extremist elements" go too far.