President Volodymyr Zelenskyy visited Ukraine's northeastern city of Kharkiv on Friday as it faces intensified Russian air attacks amid an offensive push by Moscow's forces into the north of the surrounding region.

The Ukrainian leader met senior military leaders in the city and traveled to the site of a major printing house a day after it was destroyed in a Russian missile attack that killed at least seven people.

"Today I am in Kharkiv... I also received updates on defense operations, particularly in the Vovchansk area, as well as the recovery of damaged energy infrastructure," Zelenskyy said on X.

Russian forces launched a cross-border assault on May 10, driving towards the border town of Vovchansk on one line of attack and pushing towards the village of Lyptsi on the other.

Oleksandr Syrskyi, Ukraine's top commander, said on Thursday that Russian forces were locked in street fighting in Vovchansk and that they had moved onto a defensive footing near Lyptsi.

Russia says it wants to set up a "buffer" zone in the region in what it calls a response to Kyiv's shelling of Russian border regions such as Belgorod. Russia frequently launches air strikes on Ukraine from the region of Belgorod.

The assault opened a new front in the war in what Kyiv said was an effort to divert its outnumbered troops from the east where the fiercest fighting is taking place.

Kharkiv, Ukraine's second largest city which lies some 30 km from the border with Russia, and the surrounding region have faced daily missile, drone and guided bomb strikes for months.

Most of the energy infrastructure has been severely damaged in the city, which is still home to around 1.3 million people.

"The entire city and region of Kharkiv deserve our support, gratitude, and respect," Zelenskyy said.