Ukraine: Russian troops take control of key city of Kherson - mayor

Russian forces have seized control of a key port city in southern Ukraine, the city's mayor says.

Kherson is the first major city to be taken by Russia, after heavy fighting, since it invaded a week ago.

Its mayor, Igor Kolykhaev, said Russian troops had forced their way into the city council building and imposed a curfew on residents.

Several cities have come under intense shelling in one of the most destructive days of the invasion so far.

An investigation into possible war crimes and crimes against humanity committed in Ukraine has been launched by the International Criminal Court (ICC) in The Hague.

Russia has for the first time admitted taking heavy military casualties during its attack on Ukraine, with 498 troops killed and a further 1,597 injured. Ukraine says Russia's losses run into the thousands.

Ukraine reports that more than 2,000 civilians have died since the invasion began last Thursday. The conflict has also caused 870,000 people to flee Ukraine - at a rate the UN said would make it the worst refugee crisis this century.

In a Facebook post, Mr Kolykhaev said Russian forces were in control of Kherson, a port on Ukraine's southern Black Sea coast with a population of more than 280,000 people.

He urged Russian soldiers not to shoot at civilians, saying there were no Ukrainian forces in the city.

Mr Kolykhaev called on residents to follow conditions set by Russian forces in order to "keep the Ukrainian flag flying". These include:

The capture of Kherson came as Russian forces bombarded frontline cities on Tuesday.

In the east, Ukraine's second-largest city, Kharkiv, came under a fierce aerial assault. Its mayor told the BBC shelling and cruise missile strikes were hitting residential areas and inflicting heavy civilian casualties.

But Russian efforts to encircle the capital Kyiv have slowed, with one US official saying a huge Russian convoy to the north of the city has barely moved all day.

Pictures of fighting in Ukraine have prompted international condemnation of Russia, with an overwhelming majority of UN countries calling on Moscow to immediately withdraw its troops.

Only five countries voted against the resolution, including Syria and North Korea.

The ICC said it was collecting evidence into possible violations after 39 countries called for it to open an inquiry.

Joel Gunter, BBC News, Ukraine

After more than 15 hours of continuous bombardment by Russian forces, the key Ukrainian port city of Mariupol is "near to a humanitarian catastrophe", the city's deputy mayor told the BBC.

"The Russian army is working through all their weapons here - artillery, multiple rocket launch systems, airplanes, tactical rockets. They are trying to destroy the city," Serhiy Orlov said.

Mr Orlov said Russian forces were several kilometres from the city on all sides and had launched strikes on key infrastructure, cutting water and power supplies to parts of the city. One densely populated residential district on the city's left bank had been "nearly totally destroyed", he said.

"We cannot count the number of victims there, but we believe at least hundreds of people are dead. We cannot go in to retrieve the bodies. My father lives there, I cannot reach him, I don't know if he is alive or dead."

Ukraine's army has resisted Russian forces so far in key parts of the country but the increased aerial bombardment of cities has raised fears Russia is shifting tactics.

"The Ukrainian army is very brave and they will continue to defend the city but the style of the Russian army is like pirates - they do not fight with their army, they just destroy entire districts," Mr Orlov said.

"We believe in our Ukrainian army, but we are in a terrible situation."