Shelling on Tuesday damaged a backup power line at the Zaporizhzhia nuclear power plant in Ukraine, the United Nation's nuclear watchdog said Wednesday.

The International Atomic Energy Agency said there was no immediate impact from the damage because the Russian-held plant was already disconnected from the grid.

The plant previously lost all four of its regular power lines during the conflict, according to the IAEA.

The damaged power line is one of three backup lines between the plant and a nearby thermal power station. The other two are disconnected, the IAEA said.

In recent days, the plant has relied on its sole operating reactor for power, according to the IAEA, which stressed that a "secure off-site power supply from the grid and backup power supply systems are essential for ensuring nuclear safety and preventing a nuclear accident."

-ABC News' Jason Volack

Ukrainian President Volodymyr Zelenskyy claimed during his nightly address Wednesday that several settlements have been recaptured from Russia in the Kharkiv region, though did not provide further details.

"There is good news from the Kharkiv region. However, now is not the time to name the liberated settlements," he said.

-ABC News' Jason Volack and Max Uzol

Ukrainian President Volodymyr Zelenskyy said Tuesday he was the first foreign leader to have a conversation with new United Kingdom Prime Minister Liz Truss.

Zelenskyy said in a statement on social media that he invited her to Ukraine and the two discussed security guarantees and "coordinated further pressure" on Russia.

"The goal is to stop the aggression & bring the perpetrators to justice," he said.

A Downing Street spokeswoman said in a statement that Truss reiterated the U.K.'s "steadfast support" for Ukraine in her first call with a foreign leader since taking office.

“The leaders discussed the need to strengthen global security and the measures necessary to cut off the funds fueling Putin’s war machine," the statement said.

"She praised the Ukrainians' fight for sovereignty and self-determination and said it was essential Ukraine succeeds and Russia fails," the statement continued, adding that Truss was "delighted to accept an invitation to visit President Zelenskyy in Ukraine soon."

-ABC News' Rashid Haddou

More than 1,000 children have been confirmed killed or injured in Ukraine since Russia invaded six months ago, the humanitarian organization Save the Children said Tuesday.

At least 372 children have been killed and 635 children injured since Feb. 24 -- for an average of five children killed or injured each day, according to a Save the Children analysis of verified United Nations data.

"This grim milestone marks another dark day in this senseless war. Innocent children are being injured and killed nearly every day in Ukraine," Sonia Khush, Save the Children's country director in Ukraine, said in a statement. "Ruthless violence, including the use of explosive weapons in urban areas, has taken a big toll on children over the past six months."

"Our teams inside Ukraine continue to witness the devastating impact this war is having on children and families who have endured more than eight years of conflict. The world must act now," the statement continued.

The number of civilian casualties in the war is likely "considerably" higher, the U.N. said.