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Satellite images of Ukraine show the devastation inflicted on Mariupol after Russian forces pummelled the city.
During Russia’s invasion of Ukraine, which began three weeks ago, nowhere has suffered more than Mariupol, a strategic port city of 430,000 on the Sea of Azov that has been surrounded by Russian troops for more than two weeks.
Local officials say missile strikes and shelling have killed more than 2,300 people and left residents without food, water, heat or medicine.
The images taken by satellite firm Maxar Technologies show how homes, a shopping centre, a hospital and surrounding areas were destroyed or damaged by relentless Russian strikes.
A Nasa image shows emissions spreading across Europe, created from the devastation.
Official reports show at least 200,000 people are in urgent need of removal after only about 28,800 civilians were able to escape through humanitarian corridors on Tuesday, local authorities reported.
Ukraine’s Deputy Prime Minister Iryna Vereshchuk said 400 staff and patients were being held hostage at a hospital that Russian forces captured on Tuesday.
However, Vladimir Putin’s troops have been thrown off by the challenging Ukrainian terrain and are reluctant to send tanks through rough fields and forests, hampering the army’s ability to gain a foothold in their neighbouring nation, according to British intelligence.
Britain's Ministry of Defence said for the most part Russian troops are concentrated on roads and their ability to get around is being thwarted by the lack of suitable river crossings.
Since the beginning of Russia’s full-scale invasion, Ukrainian forces have worked to destroy key bridges leading to strategic cities and towns.
As the war stretches into its fourth week, the MoD said Russian soldiers are “struggling to overcome the challenges posed by Ukraine’s terrain”.
“Russian forces have remained largely tied to Ukraine’s road network and have demonstrated a reluctance to conduct off-road manoeuvre,” the ministry said in an intelligence update on Wednesday, day 21 of the invasion.
“The destruction of bridges by Ukrainian forces has also played a key role in stalling Russia’s advance.
“Russia’s continued failure to gain control of the air has drastically limited their ability to effectively use air manoeuvre, further limiting their options.
“The tactics of the Ukrainian Armed Forces have adeptly exploited Russia’s lack of manoeuvre, frustrating the Russian advance and inflicting heavy losses on the invading forces.”
Justin Bronk, research fellow at the Royal United Services Institute (Rusi), a British defence and security think tank, said judging from the current situation it appears unlikely that Russia can successfully take Kyiv.
Mr Bronk said Mr Putin’s troops continue to target the Ukrainian capital with cruise missiles and some ballistic missiles, but their efforts to establish a presence on the ground in the city centre have so far failed.
The World Health Organisation has said that healthcare facilities and workers were being attacked at an alarming rate in Ukraine, with at least 43 attacks reported so far.
“We've never seen globally … this rate of attacks on health care,” the WHO's emergencies director Mike Ryan said.
“Health is becoming a target,” he said. “It is becoming part of the strategy and tactics of war.”
Dr Ryan said that attacks on healthcare facilities were making it harder for the WHO to send teams to Ukraine.
“This crisis is reaching a point where the health system in Ukraine is teetering on the brink.
“How can we put emergency medical teams on the ground if the very facilities that they may want to go and support are going to be attacked and going to be bombed and going to suffer catastrophic damage?”
He added: "This issue is more important than bricks and mortar. This isn't just about the destruction of buildings.
"This is about the destruction of hope.
"This is about taking away the very thing that gives people the reason to live - the fact that their families can be taken care of, that they can be cured if they're sick, that they can be treated if they're injured.
"This is this is the most basic of human rights, and it has been directly denied to people."
As well as the 43 attacks in Ukraine, the WHO has verified attacks in Afghanistan, Burkina Faso, the Democratic Republic of Congo, Libya, Nigeria, Palestine, Sudan and Syria.
The 89 separate attacks have injured 53 people and killed 35, including health workers, the WHO said.