The clash would be over control of the southern Ukrainian city of Kherson, which has been occupied for many months.

Ukraine says Russia has been strengthening its military force there while telling civilians to leave.

Meanwhile, the Deputy Prime Minister has urged Ukrainians who have left Ukraine to stay in their host nations until spring.

She says that Ukraine's energy system will not cope if they return well earlier.

Well, earlier, I spoke to Hugo Bachega, who brought me up to date.

I think it was a dramatic announcement yesterday by the deputy Prime Minister, Iryna Vereshchuk, telling Ukrainians who have left the country to stay where they are and do not return before winter is over.

And I think this shows the pressure that the system is facing here after wave of Russian attacks, targeting electricity infrastructure across the country.

The government says that about a third of the country's energy system has been destroyed as a result of those attacks and cities across the country of facing power cuts.

Residents have been told to reduce their energy consumption, and I think the fear here is that the system will be unable to cope as winter approaches.

This is a country where temperatures can drop to minus 10, 15-20°C., so there is a lot of concern here that the system will not be able to cope with rising demand as winter approaches.

And now we have this very dramatic plea from the government telling people to stay out of the country if they can.

Yeah, as you were just saying there, I mean, frankly, it's mainly because the energy systems themselves have been attacked.

Exactly, and we saw in the last two weeks Russia carrying out a wave of missile drone attacks targeting critical infrastructure across the country, cities away from the front lines.

And the Ukrainians have been saying that this is how Russia is reacting to military defeats on the battlefield by attacking civilian sites, civilian infrastructure in cities away from the front lines.

And I think we're hearing President Zelensky, senior Ukrainian officials saying that they need air defense sis to protect cities from the threat of Russian missiles, and also from those uranium made drones that Russia has been using to attack cities across the country.

Hugo, you've been keeping us up to date on the developments in Kherson.

Just give us the very latest because, you know, that is one of the cities or the only city that is in Russian control.

But the Ukrainians have really been trying to push back, but things are constantly moving and shifting and changing.

And it is very difficult to get a clear picture of what's happening there because Kherson itself, it seems that the internet has been cut off in the city and there is now a news blackout imposed by the Ukrainian authorities.

We know that Ukrainian forces are advancing along the Dnipro river, and the key target here is the city of Kherson, which is one of the largest Ukrainian cities and the Russian occupation, the capital of one of the four regions that that President Putin has claimed that he was in axing.

So it seems that this is a warning from the Ukrainian authorities.

Last night, we heard from one of the president's top advisers saying that there were no signs that Russian troops were leaving Kherson.

And in fact, they were sending in more troops to the city.

And I think you can hear the outrage has just gone off here in Kiev.

That's Hugo Bachega reporting there from Kiev.