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The two leaders spoke nearly two weeks after Russian President Vladimir Putin declared a partial mobilisation, calling up some three lakh reservists in a major escalation of his tapering invasion of Ukraine, which he portrayed as a fight to the death with the US and its allies, especially members of the North Atlantic Treaty Organisation.
"Prime Minister [Narendra Modi] reiterated his call for an early cessation of hostilities and the need to pursue the path of dialogue and diplomacy. He expressed his firm conviction that there can be no military solution to the conflict and conveyed India's readiness to contribute to any peace efforts," the Prime Minister's Office said in a statement today.
PM Modi said endangerment of nuclear facilities in Ukraine "could have far-reaching and catastrophic consequences for public health and the environment." The latest escalation came when Mr Putin less than two weeks ago announced Russia would annex "four new regions" from Ukraine and threatened the use nuclear weapons if it came to Russia's survival.
Mr Zelensky's office in a statement said he discussed with PM Modi the "holding of the so-called referenda by Russia in the temporarily occupied territories of our country". "The President noted that all the aggressor's decisions aimed at attempting illegal annexation of Ukrainian territories are null and void and do not change reality," the Ukraine government statement said.
India walks a tightrope. It abstained on a draft resolution tabled in the UN Security Council on September 30, which condemned Russia's "illegal referenda" and annexation of four Ukrainian territories.
India has also been buying Russian oil, which drew criticism from the West. Foreign Minister S Jaishankar in a strong statement in August said every country will try to ensure the best deal possible to cushion high oil prices and India was doing the same.
Before that, Mr Jaishankar told reporters in Washington that India's total oil purchase from Russia in a month is probably less than what Europe does in an afternoon.
India has been calling for an end to the war that Ukraine has been fighting for seven months, initially against incoming Russian forces, and now on the offensive after retaking key cities from Russian control.
Mr Zelensky on Saturday pledged to retake more areas in the country's eastern Donbas region from Russian forces. "Throughout this week, more Ukrainian flags have been raised in the Donbas. There will be even more in a week," he said in his evening address last week.
He spoke after Kyiv said its forces had begun moving into the key eastern town of Lyman and Ukraine's Defence Ministry posted a video of soldiers holding up a yellow and blue Ukrainian flag there. Russia's Defence Ministry said it had "withdrawn" troops from the town "to more favourable lines".
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