Biden and Putin to hold call amid Ukraine invasion fears

US President Joe Biden and Russia's Vladimir Putin will speak via video call on Tuesday, the Kremlin says, amid mounting tensions over Ukraine.

It comes after Secretary of State Antony Blinken said the US had evidence that Russia had made plans for a "large scale" attack on Ukraine.

He said it was unclear if Mr Putin had made a final decision to invade.

Russia has denied any such intention, and accused Ukraine of executing its own troop build-up.

Ukraine says Russia has deployed armoured vehicles, electronic warfare systems and 94,000 troops along their shared border.

It is the largest massing of Russian forces on its borders since it annexed Crimea from Ukraine in 2014.

Citing intelligence reports, Ukraine's Defence Minister Oleksii Reznikov said Moscow could be planning a military offensive at the end of January.

The Russian troop movement has strained already tense relations between Russia and the US.

On Friday, Mr Biden warned he would make it "very, very difficult" for Mr Putin to "go ahead and do what people are worried he may do".

The US and its European allies have discussed imposing sanctions on Russia if it takes aggressive action.

While Ukraine is not a Nato member, it has close ties with the bloc and has received Western weapons including US Javelin anti-tank missiles.

Russian officials have denied any plans for an invasion, and say the border troops are there for military exercises. Moscow has accused Nato of engaging in provocative behaviour by holding drills in the Black Sea, off Crimea.

This week Britain's most senior military officer said "we have to be on our guard" about the potential for conflict in the region.

Gen Sir Nick Carter told the BBC that he "distinctly hoped" there would not be a war with Russia, but added that Nato would have to be ready for that eventuality.

Tensions between Russia and Ukraine are nothing new. In 2014 Russia annexed Ukraine's Crimean Peninsula and soon after started to back a separatist insurgency in Ukraine's east.

More recently, Ukraine's President Volodymyr Zelensky has imposed sanctions on a powerful friend of President Putin and banned broadcasts by three pro-Russian TV stations.