Nearly 11,000 people have been forced to leave their homes in Ukraine's northeastern Kharkiv region since Russian forces launched a ground attack there on May 10, its governor said Thursday, on May 23.

Ukrainian President Volodymyr Zelensky has warned the assault, which brought Russia its biggest territorial gains in 18 months, may be the first of several waves. "A total of 10,980 people were evacuated," Kharkiv Governor Oleg Synegubov said in a post on Telegram.

Thousands fled their homes as Russian forces advanced toward border villages including Lyptsi and the city of Vovchansk.

"Fighting continues" in the area of Vovchansk, just five kilometers from the border, the General Staff said. "Our defenders are putting up a decent fight back," it added.

Moscow seized 278 square kilometers of Ukrainian territory between May 9 and 15, according to AFP calculations based on data from the Institute for the Study of War (ISW).