Russian troops close in on Kyiv's centre as residents take shelter

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Russian troops pressed toward Ukraine's capital Saturday, after a night of explosions and street fighting that sent Kyiv residents seeking shelter underground.

Britain's defence ministry said on Saturday that the bulk of Russian forces involved in the advance on Ukraine's capital Kyiv were now 30 kilometres from the city centre.

The swift movement of the troops after less than three days of fighting further imperilled a country clinging to independence in the face of a broad Russian assault, which threatened to topple Ukraine's democratic government and scramble the post-Cold War world order.

City officials in Kyiv urged residents to seek shelter, to stay away from windows and to take precautions to avoid flying debris or bullets. Many spent the night in basements, underground parking garages and subway stations.

Ukrainian authorities have urged citizens to help defend Kyiv from advancing Russian forces who invaded on Thursday in the worst European security crisis in decades.

Ukranian President Volodymyr Zelensky refused an American offer to evacuate, insisting that he would stay.

"The fight is here," he said.

But even as the fighting grew more intense, the Russian and Ukrainian governments signalled an openness to negotiations, offering the first glimmer of hope for diplomacy since Russian President Vladimir Putin launched the invasion.

Russia's Interfax news agency reported that Russian forces captured the southeastern Ukrainian city of Melitopol on Saturday, but Britain's armed forces minister denied that was the case.

Ukrainian officials were not immediately available for comment on the fate of Melitopol, a city of about 150,000 people. If the Interfax report citing the Russian Defense Ministry is confirmed, it would be the first significant population centre the Russians have seized since their invasion began.

However, British armed forces minister James Heappey told BBC radio that it was the British assessment that Russia had so far failed to capture any of its Day 1 targets for its invasion of Ukraine.

Earlier, Ukrainian officials said Russian forces fired cruise missiles from the Black Sea at Mariupol, also in the southeast, as well as Sumy in the northeast and Poltava in the east.

Kyiv Mayor Vitali Klitchsko said a missile hit a high-rise building on the city's southwestern outskirts, and a Reuters witness said another hit an area near the airport. There was no immediate word on casualties. Gunfire erupted near city-centre government buildings at around dawn, a Reuters witness said. The cause was not clear.