An ally of President Vladimir Putin yesterday issued a stark new nuclear warning to Ukraine and the West as Russia began releasing results of referendums it bills as a prelude to it annexing four Ukrainian regions.

European countries on Tuesday raced to investigate unexplained leaks in two Russian gas pipelines running under the Baltic Sea near Sweden and Denmark, infrastructure at the heart of an energy crisis since Russia's invasion of Ukraine.

The Kremlin yesterday refused to deny that Russia might close its borders to prevent an exodus of military-age men after President Vladimir Putin declared a partial mobilisation in an effort to regain the upper hand in the war in Ukraine.

Ukraine has discovered two more mass burial sites containing the bodies of hundreds of people in the northeastern town of Izium, which Kyiv recaptured from Russia this month, Ukrainian President Volodymyr Zelenskiy said.

China and India called at the United Nations for a negotiated end to the Ukraine war, stopping short of robust support for traditional ally Russia.

Russia has sought to defend its seven-month old war, with Foreign Minister Sergei Lavrov telling the United Nations that regions of Ukraine where widely-criticised referendums are being held would get Russia's "full protection" if annexed by Moscow.

Moscow replaced its top logistics general yesterday after a series of setbacks as Kremlin-held regions of eastern and southern Ukraine voted for a second day on becoming part of Russia. 

Ukraine will never forgive Russia for a shameful conflict which has thrown back Russia's development by half a century to Soviet times predating Mikhail Gorbachev, journalist and Nobel Peace laureate Dmitry Muratov told Reuters.

Voting on whether Russia should annex Kremlin-controlled regions of Ukraine opened yesterday as the West denounced the referendum that has dramatically raised the stakes of Moscow’s seven-month invasion.

A team of experts commissioned by the U.N.’s top human rights body to look into rights violations in Ukraine said Friday its initial investigation turned up evidence of war crimes in the country following Russia’s invasion nearly seven months ago.

Annexation vote begins in occupied Ukrainian territories to join Russia, West terms "sham"

Some draft-age Russians rushed to the borders on Thursday to escape their country's biggest conscription drive since World War Two, as world powers rounded on Moscow at the United Nations, accusing it of escalating the conflict in Ukraine.

Some Russian men headed swiftly to the borders yesterday after President Vladimir Putin ordered a partial mobilisation, with traffic at frontier crossings with Finland and Georgia surging and prices for air tickets from Moscow rocketing.

Russia and Ukraine carried out an unexpected prisoner swap on Wednesday, the largest since the war began and involving almost 300 people, including 10 foreigners and the commanders who led a prolonged Ukrainian defence of Mariupol earlier this year.

President Volodymyr Zelenskiy demanded a special United Nations tribunal impose "just punishment" on Russia for its invasion of Ukraine, including financial penalties and stripping Moscow of its veto power in the Security Council.

President Vladimir Putin yesterday called up 300,000 Russian military reservists, saying his promise to use all military means in Ukraine was “no bluff,” and hinting that Moscow was prepared to use nuclear weapons.

President Vladimir Putin on Wednesday ordered Russia's first mobilisation since World War Two and backed a plan to annex swathes of Ukraine, warning the West he was not bluffing when he said he'd be ready to use nuclear weapons to defend Russia.

Russian-installed leaders in occupied areas of four Ukrainian regions set out plans for referendums on joining Russia this week, a step an ally of President Vladimir Putin said would alter the geopolitical landscape forever.

An ally of Russian President Vladimir Putin and Russia's top lawmaker on Tuesday backed plans by Moscow-backed separatists in Ukraine to hold referendums paving the way for the annexation of swathes of additional territory in its former Soviet neighbour.

President Volodymyr Zelensky has vowed that there will be no let-up in Ukraine’s fight to regain its territory as Kyiv said its troops had crossed the Oskil River, preparing for an assault on Russia’s occupation forces in the eastern Donbas region.