Russian and Ukrainian forces are believed to be fighting street by street on the outskirts of Severodonetsk, a key city in Ukraine's east, the U.K. Ministry of Defense said Tuesday in an intelligence update.

"Russia's capture of Lyman supports its operational main effort, which likely remains the encirclement of Sieverodonetsk and the closure of the pocket around Ukrainian forces in Luhansk Oblast," the ministry said. "Heavy shelling continues, while street fighting is likely taking place on the outskirts of Sieverodonetsk town."

After several days of fighting, the Russian military claimed Saturday to have fully seized the strategic town of Lyman, which serves as a railway hub in the Donetsk Oblast, west of Severodonetsk.

"Russia's political goal is likely to occupy the full territory of Donetsk and Luhansk Oblasts," the ministry added. "To achieve this, Russia will need to secure further challenging operational objectives beyond Sieverodonetsk, including the key city of Kramatorsk and the M04 Dnipro-Donetsk main road."

The European Union has agreed to partially ban Russian oil exports to the EU, leaders announced on Monday.

The new ban "immediately" covers more than two-thirds of oil imports from Russia, "cutting a huge source of financing for its war machine," Charles Michel, president of the European Council, tweeted on Monday.

"We agreed in Versailles to phase out our dependency on Russian gas, oil & coal as soon as possible," European Commission President Ursula von Der Leyen tweeted. "But this requires a plan."

-ABC News' Christine Theodorou

Bridget Brink, the new U.S. ambassador to Ukraine, has arrived in Kyiv, the U.S. Embassy confirmed.

Brink was nominated by President Joe Biden in April and confirmed by the Senate on May 18.

-ABC News' Christine Theodorou

A French journalist working for cable channel BFM TV has been killed in the Luhansk region of Ukraine, according to Serhiy Haidai, the head of the Luhansk regional military administration.

French President Emmanuel Macron identified the journalist as Frédéric Leclerc-Imhoff.

"On board a humanitarian bus, alongside civilians forced to flee to escape Russian bombs, he was fatally shot," Macron tweeted. "I share the pain of the family, relatives and colleagues of Frédéric Leclerc-Imhoff, to whom I send my condolences. To those who carry out the difficult mission of informing in theaters of operations, I would like to reiterate France's unconditional support."

-ABC News' Ibtissem Guenfoud and Anna Rabemanantsoa

The United Kingdom announced a new wave of sanctions on Thursday targeting Russians involved in the barbaric treatment of children in Ukraine.

Maria Lvova-Belova, Russia's Children Rights Commissioner, tops the new list of sanctioned individuals for her alleged involvement in the forced transfer and adoption of Ukrainian children. She has been accused of enabling 2,000 vulnerable children being violently taken from the Luhansk and Donetsk regions and orchestrating a new policy to facilitate their forced adoptions in Russia.

“Today we are targeting the enablers and perpetrators of [Russian President Vladimir] Putin’s war who have brought untold suffering to Ukraine, including the forced transfer and adoption of children,” U.K. Foreign Secretary Liz Truss said in a press release.

More than 900 children were injured in Ukraine as a result of the full-scale armed aggression by the Russian Federation, according to the Ukrainian Prosecutor General’s latest report. Over 320 children were killed and more than 580 were injured.

These figures are far from being final, with more information slowly trickling in from places of active hostilities, as well as the temporarily occupied and liberated territories.

The UK's sanction list also includes Patriarch Kirill, the head of the Russian Orthodox Church, for his support and endorsement of Putin’s war.

Several members of Putin's political elite, along with four Military Colonels from a unit known to have killed, raped and tortured civilians in the Ukrainian town of Bucha, appear on the list too.

“Putin’s allies continue to choose to turn a blind eye to alleged war crimes and support his bloody offensive,” the U.K. government said. With Putin’s aggression reaching beyond Ukraine as Russian exports fuel conflict across the globe, the official press release read, the new sanctions also hit Myanmar’s military Junta.

The Junta relies heavily on Russian air assets and limiting it will cut Putin off from profiting from sales that fund his war machine, the U.K. said.

-ABC News' Edward Szekeres, Yuriy Zaliznyak, Yulia Drozd and Max Uzol