Boris Johnson told Xi Jinping, the Chinese president, to urge Vladimir Putin to pull out of Ukraine during a “frank and candid” 50-minute call on Friday.

Mr Johnson is understood to have set out the UK’s position on Ukraine during the call and said pressure should be put on Putin to withdraw his troops.

In a read-out of the call issued later, Number 10 said: “The leaders discussed a range of issues of mutual interest, including the situation in Ukraine. It was a frank and candid conversation lasting almost an hour. They agreed to speak again soon.”

It came after Joe Biden, the US president, reiterated his warning to China against coming to Russia’s aid in Ukraine. He said he had made clear that such assistance would incur “consequences” when he spoke to President Xi.

Mr Biden said he told President Xi that “he’d be putting himself at significant jeopardy” in his efforts to strengthen economic ties with the US and Europe if China were to move forward with aid to Russia.

The twin approach by Mr Johnson and Mr Biden comes at a potentially critical moment in the war in Ukraine, with Russia’s offensive appearing to have stalled and the country seeking support to help cope with severe economic hardship caused by the West’s sanctions.

Washington has been warning Beijing against helping Moscow for weeks amid reports that Russia has requested military assistance from China.

The last time Mr Johnson spoke to President Xi was in October when they discussed a range of issues, including action to address the climate crisis, global trade and economic cooperation, and security and human rights.

Number 10 added that the Prime Minister had expressed sympathy for the victims of the China Eastern Airlines jet crash earlier this week. President Xi asked him to convey his “best wishes” to the Queen on her Platinum Jubilee.

Earlier, a spokesman said: “Obviously, the Prime Minister has been talking with a lot of world leaders and quite regularly throughout the course of what has happened in Ukraine.

“This is part of the Prime Minister’s wider engagement with world leaders so he can set out our position on where we think the current situation is.”

Since Russia launched its invasion of Ukraine on Feb 24, China has taken a neutral stance publicly, backing talks to end the conflict while urging “maximum restraint” and de-escalation.