Ukraine president accuses Moscow of deliberate attack on humanitarian corridor in Mariupol as Russian forces fan out around capital and Biden prepares further trade restrictions

• Russia-Ukraine war: latest updates
• What we know on day 16

Ukraine’s president, Volodymyr Zelenskiy, has accused Russia of being a “terrorist state” after its tanks prevented a delivery of food, water and medicine to the besieged city of Mariupol, and said Moscow was capable of chemical weapon attacks.

As Russian forces appeared to be regrouping in order to encircle Kyiv and the US planned to ratchet up the economic pressure on Vladimir Putin, Zelenskiy tried to rally Ukrainians with another video address late on Thursday condemning Moscow’s relentless assault on cities.

Volodymyr Zelenskiy accuses Russia of ‘medieval’ tactics amid shelling of key cities, preventing civilians from leaving

• Ukraine-Russia war: latest updates

Ukraine’s president, Volodymyr Zelenskiy, again accused Russia of attacking fleeing civilians. Earlier on Monday his government rejected an offer from Moscow to create “humanitarian corridors” for the escape of civilians after it emerged that most of the supposedly safe routes led directly to Russia or Belarus. He accused Moscow of “medieval” tactics.

Zelenskiy rallied the nation in a fresh late-night video address, saying “You do not back down. We do not back down”, adding that “heroic” resistance was making the war “like a nightmare” for Russia. Taking viewers on a tour of his quarters in Kyiv, he promised to stay in the capital until the war was won.

A senior Russian general has been killed in fighting in Kharkiv, according to Ukraine’s defence ministry. It said its forces killed Maj Gen Vitaly Gerasimov, believed to have been first deputy commander of Russia’s 41st army.

The humanitarian crisis in Ukraine is deepening as Russian forces intensify their attacks, while food, water, heat and medicine grow increasingly scarce. Some 1.7 million Ukrainians are thought to have fled the fighting and the total could reach 5 million, the EU said.

Linda Thomas-Greenfield, the US ambassador to the United Nations, accused Vladimir Putin of having a plan “to brutalize Ukraine”, as the UN tries to negotiate evacuation corridors. Russia’s ambassador hit back, claiming Ukrainians are shelling themselves.

Britain’s home secretary is under fire for the country’s “chaotic policy” towards Ukrainians seeking refuge in the UK. Only 300 have been granted asylum so far.

Zelenskiy will address UK MPs on Tuesday via videolink and is expected to plead for more arms and a no-fly zone over Ukraine to be enforced by Nato.

China’s foreign minister has called the country’s relationship with Russia “iron clad” as Beijing continues to refuse to condemn the invasion of Ukraine despite growing pressure from the US and European Union to use its influence to rein in Moscow.