The Ukrainian President says Russia resumed missile strikes at 4am local time.
Volodymyr Zelenskyy claims that the strikes are aimed at both military and civilian targets.
137 people are said to have died in the first day of attacks, according to reports made by Sky News, as 100,000 civilians have fled their homes.
Explosions sounded before dawn in Kyiv as Western leaders scheduled an emergency meeting and Mr Zelenskyy pleaded for international help.
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The nature of the explosions was not immediately clear, but the blasts came amid signs that the capital and largest Ukrainian city was increasingly threatened following a day of fighting that left more than 100 Ukrainians dead.
Fearing a Russian attack on the capital city, thousands of people went deep underground as night fell on Thursday, jamming Kyiv’s subway stations.
Earlier, Mr Zelenskyy ordered a full military mobilisation to counter the Russian invasion which he said had led to 137 deaths.
In a decree issued late on Thursday, he said the the mobilisation would last 90 days.
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He tasked the military’s general staff with determining the number of people eligible for service and the number of reservists as well as the order of the call-up.
He also called those that had lost their lives in the invasion 'heroes' and also said hundreds more have been wounded.
Mr Zelenskyy said that despite Russia’s claim it is attacking only military targets, civilian sites also have been struck.
He added: “They’re killing people and turning peaceful cities into military targets.
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"It’s foul and will never be forgiven."
The UN Security Council will on Friday (25 February) vote on a resolution that would condemn Russia’s military aggression against Ukraine 'in the strongest terms'.
Russia earlier launched a wide-ranging attack on the eastern European country, hitting cities and bases with air strikes or shelling, as civilians piled into trains and cars to flee.
Ukraine’s government said Russia are in a 'full-scale war' that could rewrite geopolitical order.
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Mr Zelenskyy has cut diplomatic ties with Moscow and declared martial law.
“As of today, our countries are on different sides of world history,” Mr Zelenskyy tweeted yesterday (24 February).
“Russia has embarked on a path of evil, but Ukraine is defending itself and won’t give up its freedom.”
His adviser Mykhailo Podolyak said: “A full-scale war in Europe has begun… Russia is not only attacking Ukraine, but the rules of normal life in the modern world.”
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Topics: Russia, World News, Ukraine
Anish Vij