Russia's blockade of Ukrainian grain exports sparked fresh tensions with Europe as fears grow of a global food crisis, while Kyiv accused Moscow of stepping up attacks in the east of the country.
In New York, Dmitry Muratov, the Russian editor-in-chief of the independent newspaper Novaya Gazeta, auctioned off his Nobel Peace Prize gold medal for $103.5 million to benefit children displaced by the war.
Since being repelled from Kyiv and other parts of Ukraine following the February invasion, Moscow is focusing its offensive on the eastern Donbas region.
Its navy is blockading ports, which Ukraine says is preventing millions of tonnes of grain from being shipped to world markets, contributing to soaring food prices.
Prior to the war, Ukraine was a major exporter of wheat, corn and sunflower oil.
EU foreign policy chief Josep Borrell called the Russian blockade "a real war crime," which was happening "while in the rest of the world people are suffering hunger."
Moscow denies responsibility for the disruption to deliveries and, following Borrell's comments, took aim at the "destructive" stance of the West for surging grain prices.
Growing concerns about a food crisis are "the fault of Western regimes, which act as provokers and destroyers," said Foreign Ministry spokeswoman Maria Zakharova.
Ukrainian President Volodymyr Zelensky said Kyiv was engaged in "complex negotiations" to unblock grain exports, although he cautioned that there was no progress as yet.
In an address to the African Union, he also warned that the continent was a "hostage" of the conflict, and rising food prices "have already brought (the war) to the homes of millions of African families."
With the European Union set to decide at a summit this week on whether to grant Ukraine candidate status — allowing it to vie for membership — Kyiv has warned that attacks are escalating.
Ukraine said it had lost control of the village of Metyolkine. The settlement is adjacent to Severodonetsk, which has been the focus of fighting for weeks and is now largely under Russian control.
A chemical plant in Severodonetsk where hundreds of civilians are said to be sheltering was being shelled "constantly," Ukraine said.
Sergiy Gaiday — governor of the Lugansk region, which includes Severodonetsk — said the situation on the frontlines was "extremely tough."
"Every town and village under Ukrainian control in the Lugansk region is under almost non-stop fire," he said on Ukrainian TV.
He added in a statement on social media that Russia was heavily shelling Lysychansk, which sits across a river from Severodonetsk, saying there had been "catastrophic destruction."
Three people were injured and seven more missing after Ukrainian forces attacked oil drilling platforms in the Black Sea off the coast of Crimea, which was annexed by Russia in 2014, Moscow-backed Crimea leader Sergey Aksyonov said.
It was the first reported strike against offshore energy infrastructure in Crimea since Russia launched its invasion.
In the southern Kherson region — which borders Crimea, and was occupied by Russian forces in the early days of the Kremlin's offensive —Russian television was now broadcasting, the Russian army said.
Moscow has already introduced the ruble and begun distributing Russian passports in the territory, and a pro-Moscow official said Tuesday it could join Russia "before the end of the year."
The city of Kramatorsk, about 50 kilometers (30 miles) from Severodonetsk, is yet to experience the intense battles seen closer to the frontline but residents are worried the conflict will reach them.
"People worry a lot about the war, everyone is stressed," Valentina, a 57-year-old food vendor at a market, told AFP.
Another food seller, Sofiya, 16, said it was "frightening" being so close to the frontline.
"But we are trying to hold on," she said.
Stiller meets Zelensky
In the United States, Novaya Gazeta editor Muratov's Nobel medal was sold to an as yet unidentified phone bidder.
Muratov, who won the prize in 2021 alongside journalist Maria Ressa of the Philippines, and others at the auction expressed shock when the final bid came in at tens of millions of dollars more than the previous offer.
With U.S.-Russia tensions soaring, Kremlin spokesman Dmitry Peskov told NBC News that two Americans captured in Ukraine while fighting with Kyiv's military were "endangering" Russian soldiers and should be "held accountable for those crimes."
The interview is the first time the Kremlin has commented on the cases of Alexander Drueke and Andy Huynh, both U.S. military veterans, according to NBC.
Denmark meanwhile became the latest European country to warn of potential gas supply problems when its energy agency issued an early warning, as Moscow reduces supplies in response to sanctions.
In a lighter moment, Hollywood star Ben Stiller met Zelensky in Kyiv, hailing the comedian-turned-president as "my hero."
"What you've done, the way that you've rallied the country, the world, it's really inspiring," said the 56-year-old, best known for roles in "Meet the Parents" and "Night at the Museum."