Ukrainian President Volodymyr Zelenskiy in Kyiv. File photo

Talks have been ongoing, but Ukrainian President Volodymyr Zelenskiy has not been granted a direct meeting with Putin, as he has requested.

Russian and Ukrainian officials have held a series of talks, but no substantive solution to the conflict has emerged from that dialogue.

READ MORE

'Hellscape' in Mariupol where 100,000 trapped

Ukrainian President says ready to discuss deal

Zelenskiy said on Wednesday that talks between Ukraine and Russia are confrontational but moving forward, as the West plans to announce more sanctions against the Kremlin amid a worsening humanitarian crisis.

Intense Russian air strikes are turning besieged Mariupol into the "ashes of a dead land", the city council said on Tuesday, as street fighting and bombardments raged in the port city.

Russian President Vladimir Putin gestures during an event. File photo

Russian President Vladimir Putin's incursion into Ukraine has forced more than 3.5 million to flee, brought the unprecedented isolation of Russia's economy, and raised fears of wider conflict in the West unthought-of for decades.

Mariupol has become the focus of the war that erupted when Putin sent his troops over the border on what he calls a "special military operation" to demilitarise Ukraine and replace its pro-Western leadership.

The port city lies on the Sea of Azov and its capture would allow Russia to link areas in the east held by pro-Russian separatists with the Crimean peninsula, annexed by Moscow in 2014.

UN Secretary-General Antonio Guterres said he saw progress in the talks.

"From my outreach with various actors, elements of diplomatic progress are coming into view on several key issues,” and the gains are enough to end hostilities now, he said. He gave no details.

UN Secretary-General Antonio Guterres speaks during a session. File photo

Meanwhile, hundreds of thousands are believed to be trapped inside buildings, with no access to food, water, power or heat. Both civilians and Ukrainian troops were coming under Russian fire, said regional governor Pavlo Kyrylenko.

Russian forces and Russian-backed separatist units had taken about half of the port city, normally home to around 400,000 people, Russia's RIA news agency said, citing a separatist leader.

But in an early morning address, Zelenskiy held out hope for negotiations, which have yielded little since the Feb. 24 invasion began.

"It's very difficult, sometimes confrontational," he said. "But step by step we are moving forward."

Western nations plan to heap more pressure on the Kremlin.