Ukraine Says It Is Engaged in Fierce Fighting With Russia in Northeast

After surging across the border last week, Russia’s army appears to be advancing more slowly in northeastern Ukraine, Ukrainian officials and military analysts said on Wednesday, with the two sides engaged in fierce combat around villages about five miles from the border.

In a sign of the concern that Russia’s northeastern offensive is causing in Kyiv, President Volodymyr Zelensky of Ukraine canceled his participation in all international events for the coming days, including a visit on Friday to Spain where he was expected to sign a security agreement.

Civilians continued to flee areas of northeastern Ukraine under heavy shelling by Russian forces, the Ukrainian officials said, warning that their troops had to contain relentless assaults and that the situation on the ground could change fast.

Gen. Kyrylo Budanov, the head of Ukraine’s military intelligence agency, told Ukrainian television on Tuesday that conditions in the area under attack were moving “toward stabilization,” with additional Ukrainian units being rushed in to repel Russian advances. But he added that “the situation is quite tense and is changing very quickly.”

Ukraine’s General Staff said around midday Wednesday that Russian forces had “not carried out active operations since the beginning of the day” in the northeast. But it acknowledged a few hours earlier that Ukrainian troops had withdrawn from positions near two villages to avoid further casualties, allowing Russian forces to move in.

The assessments by the Ukrainian officials and analysts appeared to be supported by open-source maps of the battlefield compiled by independent groups analyzing combat footage. Those maps showed that Russian troops had gained a foothold in two settlements in the past day, a slower rate of advance than before, when they were capturing up to five settlements a day.

Russia’s Ministry of Defense said on Wednesday that it had captured two settlements in the northeast, as well as the village of Robotyne in the south. The claims could not be independently confirmed, and did not match what the open-source maps showed.

Robotyne was recaptured by Ukrainian troops last summer, in one of the few gains of Ukraine’s unsuccessful counteroffensive at the time. Should it fall back into Russian hands, it could deal a blow to the morale of the Ukrainian Army.

The two villages where Russia has gained a foothold are Lukyantsi and Vovchansk, which lie along Russia’s two lines of attack in the region — one immediately north of the large city of Kharkiv and the other a dozen miles to the east.

Oleksiy Kharkivskiy, the police chief in Vovchansk, confirmed on Wednesday that Russian troops had taken positions in several streets in the village. “Active fighting is ongoing” and the situation “is extremely difficult,” he said in a video published on Facebook from the village, in which heavy gunfire could be heard in the background.

Vovchansk has been heavily bombed since the start of Russia’s offensive operations on Friday, including with powerful guided weapons known as glide bombs that deliver hundreds of pounds of explosives in a single blast. Almost all the residents of the village, which had a prewar population of 17,000, have fled, local authorities said.

Oleh Syniehubov, the head of the Kharkiv region’s military administration, said on Wednesday that nearly 8,000 civilians had been evacuated from villages and settlements in the region. These include residents of villages on the immediate outskirts of Kharkiv which have come under increasing shelling in recent days.

Krystyna Havran, a member of the village council of Lyptsi, about 10 miles north of Kharkiv’s outer ring, said she had been scrambling to evacuate residents in recent days as the fighting got closer. “No one imagined that there would be an offensive,” she said.

Mr. Syniehubov said that Kharkiv had been targeted six times on Tuesday, including with glide bombs that hit the northern part of the city, causing heavy damage to a 12-story apartment building and injuring 22 people. A video released by the national police shows officers walking on piles of rubble inside a building and firefighters putting out a blaze.

Mykola Bielieskov, a military analyst at the government-run National Institute for Strategic Studies in Ukraine, said the Russian strikes were designed “to instill fear and make people flee from frontline urban areas.” But he added that to force Kharkiv’s 1.2 million residents to flee, Russia would have “to systematically target the city — weeks of strikes.”

Analysts say this could explain why Russia is pushing north of Kharkiv. If Russian troops secured positions in a village like Lyptsi, they would be within artillery range of the city, allowing them to pound it with shells.

Russia has also targeted power plants and substations in the Kharkiv region and other areas of Ukraine since March, part of a campaign to cut off electricity to swaths of the country and make life miserable for civilians.

The strikes have severely limited Ukraine’s available generating capacity. As a consequence, Ukrenergo, the country’s national transmission system operator, introduced emergency blackouts for households and businesses in several regions on Tuesday night and Wednesday morning, in an effort to save energy.

Power outages were limited in Kyiv, affecting only 10 percent of the consumers, according to local authorities. But Ukrenergo warned that new blackouts were likely to be introduced again on Wednesday night.

Daria Mitiuk contributed reporting.