Ukraine invasion: On day four of Russia's advance, what's happening across the country and where is under attack?
Ukraine's second-largest city comes under attack as a pipeline is destroyed and reports surface of shells hitting a radioactive waste site.
Sunday 27 February 2022 16:28, UK
Heavy fighting has broken out on the streets of Ukraine's second-largest city, Kharkiv, as troops attempt to fend off the Russian onslaught.
It follows news that a missile struck a gas pipeline in the city in the early hours of Sunday.
Video from the site showed a fireball rising from the blast.
Ukraine says '4,300 Russian troops have been killed or injured'; follow live updates
More than 200 miles to the west near Vasylkiv, south of the capital Kyiv, a Russian ballistic missile attack also set an oil depot on fire.
The flames could reportedly be seen from Kyiv, and fighting was reported to be preventing emergency services from working to extinguish the blaze.
Until Sunday, Russia's troops had remained on the outskirts of Kharkiv, a city with a population of 1.4 million about 12 miles (20km) south of the border with Russia, while other forces rolled past to press deeper into Ukraine.
But videos posted on Ukrainian media and social networks showed Russian vehicles now moving into Kharkiv and Russian troops roaming the city in small groups.
Key developments in the Ukraine crisis:
• Putin orders nuclear deterrent forces to be put on high alert
• Zelenskyy: Ukraine and Russia to hold talks at Belarus border
• Ukraine claims control of key city Kharkiv after fierce clashes
• Foreign secretary warns conflict could last 'years'
• 'Hit list' of Russian oligarchs drawn up
Okhtyrka
In Okhtyrka, there was a shred of positive news after yesterday's reported shelling of a kindergarten.
The city has seen water and electricity restored and a gas leak capped.
Okhtyrka has also now received humanitarian aid from the cities of Poltava and Zinkiv.
On Saturday, 55 people were said to have been injured and six killed when the children's centre was hit.
Read more:
What is Putin thinking?
How does Ukraine's military compare to Russia's?
Kyiv
The UK says Russian troops are continuing to advance from "multiple axis", but are meeting "strong resistance" from Ukrainian forces. The Ministry of Defence says Moscow is "prioritising the encirclement and isolation of Kyiv".
Mayor Vitali Klitschko said the bulk of the Russian forces remain around 20km (12 miles) - or "maybe less" - away.
Another explosion hit Kyiv's Zhuliany airport and Ukrainian authorities have also reported Russian missiles hitting a radioactive waste disposal site in the city overnight, but there are yet no pictures or reports of visible damage.
Ukraine has claimed around 4,300 Russian troops have been "killed or injured" so far and Dmytro Kuleba, the Ukrainian foreign minister, says "hundreds more" have been taken prisoner.