Russia says it is pulling back some of its troops from near Ukraine after a build-up raised fears of an invasion.

The defence ministry said that large-scale drills continued but that some units were returning to their bases.

There has been no independent confirmation of the withdrawal and international powers have reacted cautiously to the announcement.

More than 100,000 Russian troops have massed at Ukraine's border. Russia has always denied it is planning an attack.

Russia has deep cultural and historic ties with Ukraine, and has been seeking guarantees it will not join the Nato military alliance, something the bloc has refused to promise.

Troops began gathering in large numbers last November, bringing increasingly dire warnings about Russia's intentions. In recent days the US warned an invasion could be imminent, and moved its embassy out of the capital Kyiv.

Nato said the Russian announcement gave cause for "cautious optimism" but that they had not seen evidence of de-escalation on the ground.

In its statement, Russia's defence ministry said it was withdrawing some of the troops conducting exercises in military districts bordering Ukraine.

"A number of combat training exercises, including drills, have been conducted as planned," defence ministry spokesman Igor Konashenkov said.

Some exercises are continuing, such as a large joint Russia-Belarus drill, due to end on 20 February.

A British government source said it was waiting to see the scale of the withdrawal, saying it would have to make a difference to the ability to invade to be meaningful.

But the announcement was enough for both Ukraine and Russia to claim victory in the stand-off.

Ukraine's Foreign Minister Dymytro Kuleba said he would believe the withdrawal when he sees it but "we have managed together with our partners to deter Russia from any further escalation".

A Russian foreign ministry spokeswoman, Maria Zakharova, said the day "will go into history as the day western war propaganda failed. They have been disgraced and destroyed without a single shot being fired."

For weeks there have been regular reports of Russia increasing troop numbers near the border with Ukraine.

Now Moscow has announced that - drills over - some units are returning to base.

A sign of de-escalation? Possibly. But caution is required. The number of troops packing up and moving back is unclear.

Moscow, of course, has insisted all along it has no plans for a military escalation in Ukraine. The Russian authorities have dismissed claims by Western governments that a Russian invasion is imminent.

President Putin's spokesman said the Kremlin leader had mocked such assertions.

"Sometimes [Putin] even jokes about it," Dmitry Peskov told journalists. "He asks us to check whether they [in the West] have published the exact time that war will start."

In another development, the Russian parliament has voted in favour of asking Mr Putin to recognise the two self-declared republics of Donetsk and Luhansk in eastern Ukraine as independent.

Russia has granted citizenship to at least 720,000 people in the two areas, which are in the Donbas region where Russian-backed separatists have been fighting Ukrainian forces since 2014.

But if Mr Putin were to approve the decision and recognise the two breakaway regions, it would violate peace agreements.

"If that happens, that will be a blatant violation of Ukraine's territorial integrity and sovereignty once again, because there is no doubt that Donetsk and Luhansk are part of Ukraine within internationally recognised borders," Nato Secretary-General Jens Stoltenberg told reporters in Brussels.

Meanwhile, Germany's Chancellor Olaf Scholz is in Moscow for talks with President Putin as part of diplomatic efforts aimed at warding off a potential crisis.

Mr Scholz has faced criticism for his response to the tensions.

He has refused to commit publicly to scrapping the Nord Stream 2 gas pipeline connecting Russia and Germany in the event of Russian aggression against Ukraine, saying only that all sanctions options remain on the table.

This is in contrast to US President Joe Biden, who has said the scheme would be halted if Russia invades.