Putin cancels military onslaught on Mariupol's last line of defence

Vladimir Putin has ordered his troops to cancel plans to seize the last main stronghold of resistance in besieged city of Mariupol, instead ordering it to be blockaded so tightly that "a fly cannot pass through".

Russian forces have launched a relentless bombing campaign in the southern port, and had been planning to take over the strategically important Azovstal steel works by Thursday.

However, Putin gave the order to his defence minister Sergei Shoigu, who had previously told Putin that more than 2,000 Ukrainian fighters were still holed up in the sprawling underground complex.

"I consider the proposed storming of the industrial zone unnecessary," Putin told Shoigu in a televised meeting at the Kremlin. "I order you to cancel it."

Putin said his decision not to storm the Azovstal plant was motivated by the desire to safeguard the lives of Russian soldiers.

"There is no need to climb into these catacombs and crawl underground through these industrial facilities," he said.

"Block off this industrial area so that a fly cannot not pass through."

Putin also called on the remaining Ukrainian fighters in Azovstal who had not yet surrendered, saying Russia would treat them with respect and would provide medical assistance to those injured.

It comes as the UK's Ministry of Defence warned Russia could intensify their campaign to show some victory on their national Victory Day celebrations.

A spokesperson tweeted in an update: "Russia likely desires to demonstrate significant successes ahead of their annual 9th May Victory Day celebrations. This could affect how quickly and forcefully they attempt to conduct operations in the run-up to this date."

Mariupol would be the biggest city to be seized by Russia since it invaded Ukraine eight weeks ago in an attack that has taken longer than some military analysts expected, seen over five million people flee abroad and turned cities to rubble.