Here are the latest news developments from Russia's war in Ukraine:
1. Russia accused of 'secret construction work' at nuclear plant
Russian forces were performing secret work at Europe's largest nuclear power plant, according to Ukraine's nuclear energy operator.
Energoatom, the Ukrainian state enterprise that operates the country's four nuclear power plants, said Russian forces have carried out secret construction work over the last week at the occupied Zaporizhzhia Nuclear Power Plant.
Russian officers controlling the area would not give access to Ukrainian staff running the plant or monitors from the UN's atomic energy watchdog, Energoatom said in a statement on Tuesday.
It comes as fears rise the Kremlin might intend to make Zaporizhzhia the site of its alleged false flag operation involving a nuclear device.
Russia's defence minister Sergei Shoigu made an unsubstantiated allegation that Ukraine was preparing to launch a so-called dirty bomb.
Shoigu levelled the charge over the weekend in calls to his British, French, Turkish and US counterparts. Britain, France and the United States rejected it right away as "transparently false".
Ukraine also dismissed Moscow's claim as an attempt to distract attention from the Kremlin's own alleged plans to detonate a dirty bomb, which uses explosives to scatter radioactive waste in an effort to sow terror.
Energoatom said it "assumes" the Russians "are preparing a terrorist act using nuclear materials and radioactive waste stored at" the plant. It said there were 174 containers at the plant's dry spent fuel storage facility, each containing 24 assemblies of spent nuclear fuel.
"Destruction of these containers as a result of an explosion will lead to a radiation accident and radiation contamination of several hundred square kilometres (miles) of the adjacent territory," the company said.
It called on the International Atomic Energy Agency (IAEA) to assess what was going on.
2. 'Dirty bomb' allegations reach UN Security Council
The UN Security Council held closed-door consultations about the dirty bomb allegations at Russia's request.
Russia's UN Ambassador Vassily Nebenzya sent a five-page letter to council members before the meeting claiming that according to the Russian Ministry of Defence, Ukraine's top nuclear research instituted and Vostochniy Mining and Processing Plant "have received direct orders from (President Volodymyr) Zelenskyy's regime to develop such a dirty bomb" and "the works are at their concluding stage".
Nebenzya said the ministry also received word that this work "may be carried out with the support of the Western countries".
He warned that the authorities in Kyiv and their Western backers "will bear full responsibility for all the consequences" of using a "dirty bomb" which Russia will regard as "an act of nuclear terrorism".
Russia's deputy UN ambassador Dmitry Polyansky was asked by reporters after the council meeting what evidence Russia has that Zelenskyy gave orders to develop a "dirty bomb".
He replied: "It is intelligence information."
"We shared it in our telephone conversation with counterparts who have the necessary level of clearance," he said.
"Those who wanted to understand that the threat is serious had all the possibilities to understand that. Those who want to reject it as Russian propaganda will do it anyway."
Polyansky said the IAEA can send inspectors to investigate allegations of a "dirty bomb".
The UK's deputy UN ambassador James Kariuki told reporters after the meeting that "we've seen and heard no new evidence," and the UK, France and the US made clear "this is a transparently false allegation" and "pure Russian misinformation".
"Ukraine has been clear it's got nothing to hide," Kariuki said, adding that "IAEA inspectors are on the way".
In a related matter, Russia also asked the Security Council to establish a commission to investigate its claims that the US and Ukraine are violating the convention prohibiting the use of biological weapons.
Soon after Russia's full-scale invasion of Ukraine on 24 February, Nebenzya claimed that secret US labs in Ukraine were engaged in biological warfare — a charge denied by Washington and Kyiv.
Russia has called a Security Council meeting Thursday on Ukraine's biological laboratories and its allegations.
The Kremlin has insisted that it's warning of a purported Ukrainian plan to use a dirty bomb should be taken seriously and criticised Western nations for shrugging it off.
The dismissal of Moscow's warning is "unacceptable in view of the seriousness of the danger that we have talked about," Kremlin spokesman Dmitry Peskov said.
Speaking during a conference call with reporters, Peskov added: "We again emphasise the grave danger posed by the plans hatched by the Ukrainians."
At the White House, US President Joe Biden was asked Tuesday if Russia is preparing to deploy a tactical nuclear weapon after making its claims that Ukraine will use a dirty bomb.
"I spent a lot of time today talking about that," Biden told reporters.
The president was also asked whether the claims about a Ukrainian dirty bomb amounted to a false-flag operation.
"Let me just say, Russia would be making an incredibly serious mistake if it were to use a tactical nuclear weapon," Biden said. "I'm not guaranteeing you that it's a false-flag operation yet ... but it would be a serious, serious mistake."
Dirty bombs do not have the devastating destruction of a nuclear explosion but could expose broad areas to radioactive contamination.
3. Refugees urged not to return to Ukraine until spring
Ukrainian refugees are being urged not to return home this winter as the country battles to conserve power.
“We need to survive the winter, but, unfortunately, the networks will not survive," said deputy prime minister Iryna Vereshchuk.
Ukraine's president Zelenskyy says 30% of Ukraine's power plants have been destroyed since the war began, while Russian strikes have recently targeted Ukraine's energy infrastructure.
Rolling hours-long power cuts have been imposed in some parts of the country to try and help conserve energy.
"To return now is again to expose yourself, your children, and all your vulnerable relatives, who may be either sick or with limited mobility,” Vereshchuk added.
The International Organization for Migration (IOM) says 6.2 million Ukrainians have been displaced within the country since the war broke out in February.
Around a sixth are currently in urgent need of help, according to Stephane Dujarric, a UN spokesperson.
"There are now 1 million people in 5,670 locations where displaced people are seeking temporary shelter and support, who need help as winter approaches,” said Dujarric.
“The most urgent needs are winter clothes, blankets, portable stoves and solid fuel."
Zelenskyy has called on the world to help support Ukraine as it predicts a budget deficit of €37.9 billion next year.
4. Mercedes-Benz to sell shares to local investor in Russia
Mercedes-Benz will sell its assets in Russia to a local investor, the country's Industry and Trade Ministry announced on Wednesday.
The German carmaker is the latest to leave the Russian market amid Western sanctions following Moscow's invasion of Ukraine.
"The new owner of Mercedes-Benz's Russian subsidiaries -- car dealer chain Avtodom -- will be able to attract other companies as partners to organise joint production," the ministry stated.
Mercedes recently opened a plant around 50 kilometres from Moscow in 2019 but suspended manufacturing in March.
Japanese carmaker Nissan this month took a $687 million (€685.5 million) loss in handing over its business in Russia to a state-owned entity for one euro.
French company Renault had previously sold its majority stake in Russia's Avtovaz for just one rouble (€0.016).
Russian media have reported that -- similar to Nissan and Renault -- the deal to sell its assets may include a six-year buyback clause.
"The main priorities in agreeing the terms of the transaction were to maximise the fulfilment of obligations to clients from Russia both in terms of after-sales services and financial services, as well as preserving jobs of employees at the Russian divisions of the company," Natalia Koroleva, CEO of Mercedes-Benz Rus, said in a statement.