WARSAW: British Prime Minister Boris Johnson said his country's troop reinforcements to Poland landed on Thursday, as he visited the EU member amid growing fears of a Russian invasion of neighbouring Ukraine.

Britain had announced earlier this week that it would send an additional 350 soldiers to shore up NATO's eastern flank against any Russian aggression.

"Earlier today, the UK's 45 Commando Unit touched down in Poland," Johnson said after meeting with his Polish counterpart Mateusz Morawiecki.

"We need to work together now to achieve de-escalation and to persuade (Russian President) Vladimir Putin to de-escalate and to disengage," Johnson added.

"Poland and the UK won't accept a world in which a powerful neighbour can bully or attack their neighbours."

Hopes rise as efforts intensify to defuse Ukraine tensions

The additional troops join the 150 soldiers that Britain already contributes to NATO's enhanced forward presence in Poland.

Britain also sent another 150 soldiers to Poland in December in response to the migrant crisis on the Belarusian border.

Morawiecki thanked Johnson for his "very active role" in the West's efforts to secure peace amid the stand-off with Russia, and reiterated the importance of European unity.

"It is about time that the world, and Western Europe in particular, rise from its geopolitical slumber," he added.

Johnson is due to meet with British troops deployed in Poland later Thursday, as well as with Polish President Andrzej Duda.