Sharjah 24: Ukrainian leader Volodymr Zelensky said all issues would be on the table if Russia's Vladimir Putin agreed to direct talks to end the war, including contested Crimea and Donbas, but he warned his country would be "destroyed" before it surrenders.

On the ground, there was no let-up in the violence, with Kyiv under a new 35-hour curfew after Russian strikes reduced a Kyiv shopping mall to rubble, and the Pentagon saying Moscow was stepping up air and sea operations.

President Joe Biden meanwhile warned that Putin was considering using chemical and biological weapons in Ukraine as he held talks with European leaders on what he called Moscow's increasingly "brutal tactics".

Nearly a month into the conflict, there has been little progress in talks between the two sides, and Zelensky has repeatedly urged direct discussions with his Russian counterpart.

He insisted again on Monday that a meeting with Putin "in any format" was needed to end the war.

"If I have this opportunity and Russia has the desire, we would go through all the questions," he told Ukrainian journalists in an interview published by media outlet Suspilne.

"Would we solve them all? No. But there is chance, that we partially could -- at least to stop the war," he added.

Zelensky said he was even willing to discuss Russian-occupied Crimea and the breakaway Russian regions in Donbas, though he insisted he still believes they must be returned to Ukraine.

"At the first meeting with the president of Russia, I am ready to raise these issues," he said, adding that any agreement involving "historic" changes would be put to a national referendum.

"This is a very difficult story for everyone. Crimea and Donbas... And to find a way out, we need to take this first step, which I spoke about: security guarantees, the end of the war," he added.

He repeated his assertion that Ukraine "already understood" it could not join NATO but he added that his countrymen would not simply "hand over" the capital, the eastern city of Kharkiv, or the heavily bombarded and besieged southern port of Mariupol.

"Ukraine cannot fulfil Russian ultimatums," he said. "We should be destroyed first."