Russian troops pushed deeper into a key eastern Ukrainian city Monday, fighting street by street with Kyiv's forces in a battle that has left Sievierodonetsk in ruins. In a bid to pressure Moscow to end the war, the European Union agreed to embargo most Russian oil imports by the end of the year.

As Moscow's advance on Sievierodonetsk increased in intensity, Russian forces also shelled parts of Ukraine's northeast, and a struggle continued for control of a southern region. Ukrainian President Volodymyr Zelenskyy, meanwhile, said Russia has prevented the export of 22 million tons of Ukrainian grain, contributing to a growing global food crisis.

Military analysts described the fight for Sievierodonetsk as part of a race against time for the Kremlin. The city is important to Russian efforts to quickly complete the capture of the eastern industrial region of the Donbas before more Western arms arrive to bolster Ukraine’s defense. Moscow-backed separatists already held territory in the region and have been fighting Ukrainian troops for eight years.

“The Kremlin has reckoned that it can’t afford to waste time and should use the last chance to extend the separatist-controlled territory because the arrival of Western weapons in Ukraine could make it impossible," Ukrainian military analyst Oleh Zhdanov said.

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In a potential setback for Ukraine, U.S. President Joe Biden appeared to dismiss reports that the U.S. was considering sending long-range rocket systems to the country.

But the European Union approved additional sanctions on Russia. As part of a long-delayed financial support package to help Ukraine, EU leaders agreed Monday to embargo most Russian oil imports into the 27-nation bloc by year-end. The agreement came after Zelenskyy asked the EU to target Russian oil exports so Moscow “feels the price for what it is doing against Ukraine.”

The embargo covers Russian oil brought in by sea, allowing a temporary exemption for imports delivered by pipeline. EU Council President Charles Michel said the agreement covers more than two-thirds of oil imports from Russia. Ursula Von der Leyen, the head of the EU’s executive branch, said the move will “effectively cut around 90% of oil imports from Russia to the EU by the end of the year.”

In an effort to punish and divide the West over its support for Ukraine, Russia has cut off natural gas to a handful of European countries. In its latest move, Russian state gas giant Gazrpom said it will halt gas supplies to Dutch gas trader GasTerra starting Tuesday.

Russia also ramped up its actions on the battlefield. In his nightly video address, Zelenskyy said the situation in the Donbas remains “extremely difficult” as Russia has put its army’s “maximum combat power” there.

The Ukrainian military said Russian forces reinforced their positions outside Sievierodonetsk, a city 145 kilometers (90 miles) south of the Russian border in an area that is the last pocket of Ukrainian government control in Luhansk.

Sievierodonetsk Mayor Oleksandr Striuk said the city has been “completely ruined.” Artillery fire has destroyed critical infrastructure and damaged 90% of the buildings, and power and communications have been largely cut to a city that was once home to 100,000 people, he said.

“The number of victims is rising every hour, but we are unable to count the dead and the wounded amid the street fighting,” Striuk told The Associated Press in a phone interview, adding that Moscow’s troops advanced a few more blocks toward the city center.

He said that only about 12,000 to 13,000 residents remain, sheltering in basements and bunkers to escape the Russian bombardment. The situation recalls the siege of Mariupol, which trapped residents and led to some of the worst suffering of the war. More than 20,000 are feared dead in Mariupol.

Striuk estimated that 1,500 civilians have died in Sievierodonetsk since the war began from Russian attacks and from dire conditions that include a lack of medicine and medical treatment.

A 32-year-old French journalist, Frédéric Leclerc-Imhoff, died Monday near Sievierodonetsk when he was hit by shrapnel from shelling while covering Ukrainian evacuations, according to his employer, French broadcaster BFM TV.

Zelenskyy said Leclerc-Imhoff was the 32nd media worker to die in Ukraine since Russia invaded on Feb. 24.

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Governors of the Luhansk and Donetsk regions — which make up the Donbas — said six civilians, including the journalist, were killed in shelling. Authorities in Kharkiv, Ukraine's second-largest city, also reported one person died in shelling there.

Zelenskyy said Russian troops also shelled the Sumy region near the Russian border, and the struggle continued for the southern Kherson region, which has been largely controlled by Russian troops since the early days of the war. Russia-installed officials there said they would ask the Kremlin to annex it, while Kyiv, in turn, has vowed to liberate the region.

The Russian advance in Sievierodonetsk and Lysychansk on either side of the strategically important Siverskiy Donetsk River is part of an all-out push, said Zhdanov, the Ukrainian military analyst. He said the intensity of the latest fighting and the influx of Russian troops have surprised Ukrainians, who are trying to hold out until more weapons arrive.

On Monday, Biden told reporters that there are no plans for the United States to send long-range rocket systems to Ukraine, amid reports that the move is being considered.

Dmitry Medvedev, the deputy head of Russia’s Security Council, called it a “reasonable” decision. He said that “otherwise, if our cities come under attack, the Russian armed forces would fulfill their threat and strike the centers where such criminal decisions are made.”

Medvedev added that “some of them aren’t in Kyiv.”

In the Kherson region, the Russia-installed deputy head of the regional administration, Kirill Stremousov, told Russia’s Tass state news agency that grain from last year’s harvest is being delivered to Russian buyers, adding that “obviously there is a lot of grain here.”

Russia has pressed the West to lift sanctions against it as it seeks to shift the blame for the growing food crisis, which has led to skyrocketing prices in Africa.

Zelenskyy accused Moscow of “deliberately creating this problem” and said Russia’s claim that sanctions are to blame is a lie. He said sanctions haven’t blocked Russian food, and he accused Russia of stealing at least a half million tons of Ukrainian grain.