British PM Johnson to speak to Russia's Putin later on Monday

British Prime Minister Boris Johnson will speak to Russian President Vladimir Putin later on Monday, part of a flurry of activity in London to try to put pressure on Moscow over its troop buildup on the border with Ukraine.

"The prime minister is expected to speak to President Putin this afternoon," the spokesman told reporters, adding that foreign minister Liz Truss would make a statement to parliament on the Russia sanctions regime.

Johnson and Truss will travel to Ukraine on Tuesday, he said.