Liz Truss has suggested the Russian invasion of Ukraine could mark the “beginning of the end” for Vladimir Putin, as she warned the conflict could last a “number of years”.

       As the Kremlin’s military offensive entered its fourth day, the foreign secretary insisted Moscow had not expected the resistance shown by the Ukrainian people and their president.

       With opposition parties calling for stronger sanctions, Ms Truss also told Sky News the UK government had drawn up a “hit list of oligarchs” whose property and private jets would be targeted.

       And she suggested the cost to the Russian state of a range of economic sanctions could mean the “beginning of the end for Putin”, with “serious consequences” for him personally.

       “I fear that he is prepared to use the most unsavoury means in this war,” she said, as she spoke of the possibility of Russia using “even worse weapons”.

       Recommended Ukraine-Russia latest news: Defiant Zelensky remains in Kyiv What are the issues between Ukraine and Russia? The crisis explained

       “He should be aware the International Criminal Court is already looking at what is happening in Ukraine. There will be serious consequences for him and for the Russian government,” she added.

       Her remarks come after Boris Johnson praised the resistance of the Ukrainian people but warned that there were “grim days” ahead for the eastern European country.

       Speaking on Sunday, Ms Truss said the British government would continue to provide both military and economic aid to the country.

       However, she continued: “I fear this this will be a long haul. This could be a number of years. What we do know is Russia has strong forces, but we know the Ukrainians are brave, they are determined to stand up for their sovereignty.”

       Damage is seen on a large residential tower in Kyiv after it was hit by a missile on 2 February

       (Getty)

       On Sunday, the Ministry of Defence posted an intelligence update in respect of the situation in Ukraine, which said: “Ukrainian forces have engaged the remnants of Russian irregular forces within the city of Kyiv for the second night in a row, fighting has been at a lower intensity than the previous evening.

       “After encountering strong resistance in Chernihiv, Russian forces are bypassing the area in order to prioritise the encirclement and isolation of Kyiv.

       Recommended Ukraine invasion spotlights the delicate state of democracy Grannies armed with Molotov cocktails: Kyiv residents prepare for Russian troops EU sanctions to go ahead despite planned Ukraine-Russia meeting – Irish minister

       “Intensive exchanges of rocket artillery overnight have been followed by heavy fighting between Russian and Ukrainian forces in Kharkiv.

       “Russian forces are continuing to advance into Ukraine from multiple axis [sic] but are continuing to be met with stiff resistance from the Ukrainian armed forces.”