Ukrainian President Volodymyr Zelenskyy said on Wednesday that Ukrainian troops have recaptured several towns in the Kharkiv region in the country's northeast from Russian forces.
"This week we have good news from Kharkiv region," Zelenskyy said in his daily address, according to the AFP news agency. He added that "now is not the right time to name those settlements, where the Ukrainian flag has returned".
Observers have reported a breakthrough by Ukrainian forces in the Kharkiv region in recent days, with no official confirmation of the potential gains.
Kharkiv region has been partly occupied by Russian troops since the start of the invasion launched on February 24.
The city of the same name is regularly targeted by bombardments, but the Russian troops have never managed to seize it.
Near the start of the war, Russian forces shelled a nuclear research institute in Kharkiv, setting buildings on fire.