Ukraine wants to hold talks with Russia within 48 hours

Ukrainian Foreign Minister Dmytro Kuleba said Moscow had not responded after Kyiv on Friday  invoked a part of the Vienna Document, a set of security agreements, to demand Moscow explain its military activities.

Russia has more than 100,000 troops massed near Ukraine, which is not part of the Atlantic military alliance, and the United States - while keeping open the diplomatic channels that have so far failed to ease the crisis - has repeatedly said an invasion is imminent.

Ukrainian Defence Minister Oleksii Reznikov said on Twitter that Kyiv had so far received almost 1,500 tonnes of ammunition from allies delivered on 17 flights, including about 180 tonnes from the US.

The Kremlin said Mr Putin told Mr Biden during their call on Saturday that Washington had failed to take Russia’s main concerns into account, and that it had received no “substantial answer” on key elements of its security demands.