Thousands evacuate as Russia presses Ukraine villages

Thousands more civilians have fled Russia's renewed ground offensive in Ukraine's northeast that has targeted towns and villages with a barrage of artillery and mortar fire, officials say.

The intense battles have forced at least one Ukrainian unit to withdraw in the Kharkiv region, capitulating more land to Russian forces across less defended settlements in the so-called contested "grey zone" along the Russian border.

Meanwhile, a 10-storey apartment block collapsed in the Russian city of Belgorod, near the border, with several deaths and injuries reported.

Russian authorities said the building collapsed following Ukrainian shelling.

Ukraine has not commented on the incident.

At least 4000 civilians have fled the Kharkiv region since Friday when Moscow's forces launched the operation, Governor Oleh Syniehubov said on social media.

Heavy fighting raged on Sunday along the northeast front line, where Russian forces attacked 27 settlements in the past 24 hours, he said.

Analysts say the Russian push is designed to exploit ammunition shortages before promised Western supplies can reach the front line.

Ukrainian soldiers said the Kremlin was using the usual Russian tactic of launching a disproportionate amount of fire and infantry assaults to exhaust their troops and firepower.

It comes after Russia stepped up attacks in March targeting energy infrastructure and settlements, which analysts predicted were a concerted effort by Moscow to shape conditions for an offensive.

Ukrainian President Volodymyr Zelenskiy said disrupting Russia's offensive in the area was a priority and Kyiv's troops were continuing counteroffensive operations in seven villages around the Kharkiv region.

"Disrupting the Russian offensive intentions is our number one task now," Zelenskiy said.

"Whether we succeed in that task depends on every soldier, every sergeant, every officer,."

The Russian Defence Ministry said on Saturday that Moscow's forces had captured five villages on the border of Ukraine's Kharkiv region and Russia.

These areas were likely poorly fortified due to the dynamic fighting and constant heavy shelling, easing a Russian advance.

Ukraine's leadership has not confirmed Moscow's gains.

A Ukrainian unit said that they had been forced to retreat in some areas and that Russian forces had captured at least one more village late on Saturday.

In a video on Saturday evening, the Hostri Kartuzy unit, part of the special forces' detachment of Ukraine's national guard, said they were fighting for control of the village of Hlyboke.

"Today, during heavy fighting, our defenders were forced to withdraw from a few more of their positions, and today, another settlement has come completely under Russian control," the fighters said in the clip.

"As of 20:00, fighting for the village of Hlyboke is ongoing."

The US-based Institute for the Study of War said on Saturday it believed claims that Moscow had captured Strilecha, Pylna, Pletenivka and Borsivika were accurate, and that geolocated footage also appeared to show Russian forces had seized Morokhovets and Oliinykove.

It described the recent Russian gains as "tactically significant".

In the war's early days, Russia made a botched attempt to quickly storm Kharkiv but retreated from its outskirts after about a month.

Seven months later in 2022, Ukraine's army pushed them out of Kharkiv.

The bold counterattack helped persuade Western countries that Ukraine could defeat Russia on the battlefield and merited military support.