As Russian and Ukrainian forces traded blistering artillery barrages and engaged in fierce fighting across towns and villages in eastern Ukraine, European Union leaders gathered on Tuesday for the second day of a summit aimed at pressing efforts to punish Russia while bolstering the battered Ukrainian economy.

After weeks of tough talks finally led to agreement on an embargo on billions of dollars’ worth of Russian oil and a package of sanctions aimed at the Russian economy, European leaders are now wrestling with how to help Ukraine export millions of tons of grain despite an effective naval blockade from Russia that has kept ships stranded at port.

But finding a way to quickly get millions of tons of grain out of Ukrainian warehouses — an issue essential for the stability of the global food supply and for tens of millions of people who could face hunger or even famine — involves a host of challenges almost inextricable from the uncertainties of the war.

At the same time, European leaders are working on a broader economic relief package worth more than $9 billion to be delivered over the course of 2022.

Fighting in eastern Ukraine has reached pitched levels this week, according to Ukrainian and Russian officials, as Russia directed the might of its artillery and missile systems on an already devastated 75-mile stretch of land straddling the eastern regions of Donetsk and Luhansk.

For weeks, they have rained fire on the last Ukrainian-controlled city in the Luhansk region, Sievierodonetsk, forcing civilians unable to flee to cower in basements and bomb shelters.

“I am horrified to see Sievierodonetsk, the thriving city where we had our operational headquarters, become the epicenter of yet another chapter of the brutal war in Ukraine,” Jan Egeland, secretary-general of the Norwegian Refugee Council, said on Tuesday.

Serhiy Haidai, the head of Luhansk regional military administration, acknowledged that Russian forces had occupied parts of Sievierodonetsk and were “gradually moving toward downtown.” But he added that they had yet to encircle the city, leaving Ukrainian soldiers a route in and out.

In other developments:

  • Gazprom, Russia’s state-run energy giant, cut its supply early Tuesday to a Dutch company, GasTerra, because the company had refused to pay in rubles.

  • President Volodymyr Zelensky of Ukraine offered condolences in his nightly address to the family and colleagues of the French journalist Frédéric Leclerc-Imhoff, who was killed on Monday in eastern Ukraine.

  • Kalush Orchestra, the Ukrainian band that won the Eurovision Song Contest, auctioned off its trophy and the lead singer’s signature pink bucket hat to buy drones for the Ukrainian army.