Vladimir Putin putting Russia's nuclear forces on high alert is an attempt to distract people from "what's going wrong in Ukraine", Defence Secretary Ben Wallace has said.

Mr Wallace said Mr Putin was engaged in a "battle of rhetoric" by trying to "remind the world" he had a deterrent.

He said Russia was behind schedule on its invasion of Ukraine and Ukrainians were putting up a "very strong fight".

Mr Putin has said his order was due to aggression by the West and Nato.

His announcement does not mean Russia intends to use its nuclear weapons.

But it attracted international condemnation, with the US branding it an "unacceptable escalation".

The EU later unveiled an unprecedented new raft of further sanctions against Moscow, including banning all Russian aircraft from its airspace and barring state media outlets Sputnik and Russia Today from EU territory.

The EU said it would also fund the purchase and delivery of weapons to Ukraine.

BBC Security Correspondent Gordon Correra suggests Mr Putin's aim is likely to try and deter Nato support for Ukraine by creating fears over how far he is willing to go - and creating ambiguity over what kind of support for Ukraine he would consider to be too much.

Speaking to BBC Breakfast on Monday, Mr Wallace said he understood concerns over Mr Putin's order, revealing his own 12-year-old son had called him about it.

He said: "We don't see or recognise in the sort of phrase or the status he described as anything that is a change to what they have currently as their nuclear posture.

"This is predominantly about Putin putting it on the table just to remind people, remind the world, that he has a deterrent."

The defence secretary said that Britain was also a nuclear power and that its deterrent had "kept our security for decades".

"It [the UK's nuclear deterrent] does keep us safe and that's why I would say to parents up and down this country we will not do anything to escalate in that area.

"We will not do anything to feed any miscalculation. We take it very, very seriously."

Meanwhile, Mr Wallace said Moscow's invasion of Ukraine was not going to plan, with "significant casualties" and protests against it in Russia.

He said that as a result, Russia's attack was likely to be become "more violent" and could see it "indiscriminately" bombing Ukrainian cities.

Russian President Vladimir Putin is now in a tight spot and that's dangerous.

This long-planned invasion of his neighbour is not going to plan, although his forces are making some progress in the south.

Beyond Ukraine's borders, the international reaction has been far swifter and more severe than he would have expected, inflicting serious damage on the Russian economy that could end up threatening his authority at home.

So what comes next? On the sanctions, Moscow will retaliate in some form - possibly with a major cyber-attack on Western institutions.

But Putin's more immediate task is to show he is winning in Ukraine.

Barring the unlikely chance of a peace deal, we can expect to see an intensification of the Russian offensive on Ukraine's cities.

Judging by previous Russian actions in Chechnya and Syria there will be scant regard for the safety of civilians, and Moscow still has some devastating weapons at its disposal that it has yet to use.

The government is looking at measures to support Ukrainian refugees, after its announcement for some family members of British nationals, according to BBC Political Correspondent Nick Eardley.

Russia's military assault has entered its fifth day, with cities across Ukraine on high alert after the capital Kyiv and major centres of Kharkiv and Chernihiv were targeted by Russian forces overnight.

All three cities remain under Ukrainian control, but Russia made some progress in the south, taking the port town of Berdyansk, and clashes are ongoing in the strategically important port city of Mariupol.

"Logistical failures and staunch Ukrainian resistance continue to frustrate the Russian advance," it said.

Ukrainian President Volodymyr Zelensky has warned the next 24 hours will be "crucial".

Negotiators for Kyiv and Moscow are meeting for talks today on Ukraine's border with Belarus.

Mr Zelensky said on Sunday that he did not expect a breakthrough from the talks but said he would attend because of the "small chance to end the war".

The UN General Assembly - made up of 193 member states - is set to meet later to discuss the situation in Ukraine.

After a phone call with Mr Zelensky at the weekend, Prime Minister Boris Johnson said things "are not going all the way of President Putin" and Ukrainians had been "fighting heroically" and with "great success" to repel Russian forces.