A charred Russian tank is seen, amid Russia's invasion of Ukraine, in the Sumy region, Ukraine, March 7, 2022.  Irina Rybakova/Press service of the Ukrainian Ground Forces/Handout via REUTERS
A charred Russian tank is seen, amid Russia's invasion of Ukraine, in the Sumy region, Ukraine, March 7, 2022. Irina Rybakova/Press service of the Ukrainian Ground Forces/Handout via REUTERS Reuters / IRINA RYBAKOVA/PRESS SERVICE OF

Russia announced a new ceasefire in Ukraine on Wednesday to let civilians flee besieged cities, but there were only limited signs of progress providing escape routes for hundreds of thousands of people trapped without medicine or fresh water.

The governor of Sumy, an eastern city, said civilian cars were leaving for a second day through a safe corridor set up to Poltava further west.

But by midday in Ukraine there was no confirmation that any of the other evacuation corridors had been successfully opened, including a route out of Mariupol, seen as the most urgent, where the Red Cross has described conditions as "apocalyptic".

The mayor of Enerhodar, site of Europe's biggest nuclear power plant which Russian forces seized last week in a battle that raised global alarm, said humanitarian supplies would be allowed in and buses would take residents out on the way back.

The greatest humanitarian concern is Mariupol, a southern port surrounded by Russian troops for more than a week.

Residents there have been sheltering underground from relentless bombardment, unable to evacuate their wounded, and with no access to food, water, power or heat. Local ceasefires to let them leave have failed since Saturday.

Kyiv said 30 buses and eight trucks of supplies failed to reach it on Tuesday after they came under Russian shelling in violation of the ceasefire. Moscow has blamed Kyiv for failing to halt fire.

More than 2 million people have fled Ukraine since President Vladimir Putin launched the invasion nearly two weeks ago. Moscow calls its action a "special military operation" to disarm its neighbour and dislodge leaders it calls "neo-Nazis."

Kyiv and its Western allies dismiss that as a baseless pretext for an unprovoked war against a democratic country of 44 million people.

In recent days, Russia has also accused Ukraine of having tried to develop biological or nuclear weapons. On Wednesday, the Kremlin said Washington must explain what Moscow described as Ukrainian biological weapons labs. Western countries call that an attempt to fabricate a new pretext for the invasion retroactively.

Ukraine's nuclear power plant operator said it was concerned for safety, both at Enerhodar and at Chernobyl, mothballed site of the world's worst nuclear disaster, where it said a power cut due to fighting meant spent nuclear fuel could not be cooled.

'RETALIATORY MEASURES'

The war has swiftly cast Russia into economic isolation never before visited on such a large economy. The United States said on Tuesday it was banning imports of Russian oil, a major policy change after energy was previously exempted from sanctions.

Western companies have swiftly withdrawn from the Russian market. In a stark symbol, McDonalds said on Tuesday it was shutting its nearly 850 restaurants in Russia. Its first, which drew huge queues to Moscow's Pushkin Square when it opened in 1990, had been an emblem of the end of the Cold War.

Starbucks , Coca-Cola, Pepsi and others made similar announcements. Imperial Brands, the UK-listed maker of Winston cigarettes, joined the stampede out on Wednesday, shutting its factory in Volgograd.

Russia's ruling United Russia party said it proposed seizing assets of foreign companies that leave.

"We will take tough retaliatory measures, acting in accordance with the laws of war," Andrei Turchak, secretary of the party's council, wrote on its website.

Banishing Russia, the world's top exporter of combined oil and gas, from markets is sending shockwaves through the global economy at a time when inflation in the developed world is already at levels not seen since the 1980s. Retail fuel pump prices have surged to records. [O/R]

Both Ukraine and Russia are also major global exporters of food and metals. Prices of grain and food oils have soared worldwide, punishing poor countries in the Middle East, Africa and Asia. Trade in nickel, critical in electric vehicle production, was called off on Tuesday in London after the price more than doubled.

Ukraine said on Wednesday it was halting exports of rye, barley, buckwheat, millet, sugar, salt and meat for the rest of the year.

'WAR MACHINE'

U.S. President Joe Biden acknowledged that Americans' bills would rise but said it was necessary to restrict Russia's ability to wage war.

"The American people will deal another powerful blow to Putin's war machine," he said.

Britain said it would phase out Russian oil by the end of 2022, while the European Union published plans to cut its reliance on Russian gas by two thirds this year.

China, which signed a friendship pact with Russia three weeks before the invasion, has yet to join the West in condemning Moscow or imposing sanctions.

U.S. Commerce Secretary Gina Raimondo told the New York Times Washington could "essentially shut" down Semiconductor Manufacturing International Corp or any Chinese companies that kept supplying chips or other advanced technology to Russia.

U.S. intelligence chiefs told lawmakers on Tuesday that China appeared to have been unsettled by difficulties Russia was facing in Ukraine and the strength of the Western reaction.

High oil prices prompted by Russia's invasion could cut a full percentage point off the growth of big developing economies such as China, Indonesia, South Africa and Turkey, a World Bank official said.

'OUR TASK'

Western countries believe Moscow had aimed to quickly topple the Kyiv govenrment in a lightning strike, and is being forced to adjust after underestimating Ukrainian resistance. Russia has taken substantial territory in the south but has yet to capture any major cities in northern or eastern Ukraine, with an assault force stalled on a highway north of Kyiv.

Russia is desperate for some kind of victory in cities like Mariupol and Kyiv, before it negotiates peace, Vadym Denysenko, an adviser to Ukraine's interior minister, wrote on Facebook on Wednesday. "Therefore, our task is to withstand for the next 7-10 days," he said.

Ukrainians fear the next big target will be Odessa, Ukraine's main Black Sea port. Residents are preparing to defend the historic city of 1 million, a polyglot centre of culture with wide resonance for Ukrainians and Russians alike. A giant blue and yellow banner reading "Odessa-Ukraine" was draped atop sandbags in the near-deserted city centre.

"We did not surrender Odessa to Hitler, and we will not surrender it to anyone else," said Galyna Zitser, director of the Odessa Philharmonic, which on Tuesday put on its first performance since the crisis began.