Ukraine has regained control of Kharkov, the country's second-largest city, after fighting with Russian forces, the regional governor said on Sunday. 

Kharkiv’s Governor Oleh Synyehubov made the statement on Telegram, saying Ukrainian armed forces including police and defense units had full control of the city, and were "cleansing" the city from the enemy.

According to footages in circulation, heavy clashes erupted between Ukrainian forces and Russian army in the city late Saturday.

Separately, Ukrainian government ombudsman Lyudmyla Denysova accused Russia of killing civilians by targeting residential areas, hospitals, kindergartens and schools.

Russia’s intervention on Thursday came just days after it recognized two separatist-held enclaves in eastern Ukraine.

On the fourth day of the attacks, Ukraine’s President Volodymyr Zelenskyy said Ukraine is ready for peace talks, but not in Moscow’s preferred venue of Gomel, Belarus, and instead suggested Istanbul, Warsaw, Baku, or Budapest.

At least 368,000 Ukrainians have fled the country since the beginning of Moscow’s assault, according to the UN Refugee Agency.

Western powers have imposed financial sanctions on Moscow, and decided to supply Ukraine with weapons and ammunition.