Ukrainian officials said waves of Russian missile attacks on Kyiv and other major cities had damaged key infrastructure sites as local authorities warned of potential cuts in electricity and water supplies in the first major attacks since the start of the year.

Air-raid sirens blared in much of the country on January 14 as strikes were reported in the capital, along with in the western city of Lviv, Kharkiv in the east, Odesa in the south, and Dnipro in the south-central region, where officials said an apartment block had been struck by Russian missiles, killing at least five people.

Meanwhile, British Prime Minister Rishi Sunak has informed Kyiv that Britain intends to send main battle tanks and artillery support to aid Ukraine's war effort against invading Russian forces, a move Moscow condemned.

"The prime minister outlined the U.K.'s ambition to intensify our support to Ukraine, including through the provision of Challenger 2 tanks and additional artillery systems," a British spokesperson said.

The attack on the Ukrainian capital was announced on Telegram by the city's military administration on January 14.

The office of Ukrainian President Volodymyr Zelenskiy advised residents of Kyiv to seek shelter, while explosions that sounded similar to missiles being shot down by air-defense forces were reportedly heard in the city.

Kyiv Mayor Vitali Klitschko said in a series of posts on Telegram that explosions were reported in the city's eastern residential Dniprovskiy district and parts of a missile had crashed in an uninhabited part of the Holosiyivskiy district. Klitschko said no casualties had been reported and a fire at a nonresidential building in the Holosiyivskiy district had been extinguished.

According to presidential office deputy head Kyrylo Tymoshenko, the attack targeted "critical infrastructure." Tymoshenko also wrote on Telegram that a residential building in the village of Kopyliv in the Kyiv region was struck, breaking windows of residential buildings. He said that as of late morning there was no information regarding any possible victims related to that incident.

Ukrainian Air Force spokesman Yuriy Ihnat said the missiles had been fired from a high trajectory from the north, suggesting they were ballistic missiles that Ukraine is unable to shoot down and was not able to detect in time to immediately alert civilians of an air raid.

The fresh attacks came a day after Ukraine and Russia gave conflicting accounts of the situation in the eastern Ukrainian town of Soledar, the site of intense fighting between Russian and Ukrainian forces in recent weeks.

WATCH: . The strategic town sits on a vast network of salt-mine tunnels that cover an estimated 200 kilometers.

In his nightly video address on January 13, Zelenskiy rejected claims by Russia's Defense Ministry that it captured the strategically important salt-mining town in the eastern Donetsk region.

"The tough battle for the Donetsk region continues. The battle for Bakhmut and Soledar, for Kreminna, for other towns and villages in the east of our country continues," Zelenskiy said. "Although the enemy has concentrated its greatest forces in this direction, our soldiers -- the Armed Forces of Ukraine, all defense and security forces --- are protecting the state."

The capture of Soledar, which could give Russian forces a hub to cut off Ukrainian supply lines while also providing a staging ground for attacks on the nearby city of Bakhmut, would be Moscow's most substantial military gain in its war against Ukraine in months.

Kyiv and Washington, however, have suggested the heavy loss of Russian troops and the destruction of the city have lessened Soledar's strategic value.

The Russian Defense Ministry has claimed hundreds of Ukrainian soldiers have been killed in heavy fighting in Soledar this week. Ukrainian officials have said more than 500 civilians are trapped inside the town, including 15 children.

The private and controversial Russian mercenary group Vagner is reportedly heavily involved in the Russian effort to capture Soledar.

After initial success in taking Ukrainian territory after Russia's all-out invasion in February, the Russian military suffered setbacks in the south and the eastern Donbas region. The Russian military has focused on Soledar as key to the success of its new offensive.

The head of the eastern Kharkiv region, Oleh Synehubov, said the regional capital, Kharkiv, was hit by two Russian S-300 missiles early on January 14.

The strikes hit energy infrastructure and industrial in the city, Ukraine's second-largest, according to Synehubov.

In western Ukraine, Maksym Kozytskiy, head of the Lviv regional military administration, said "a critical infrastructure facility" had been hit in the region and warned of electricity and water supply disruptions. Lviv, far away from the front lines, had in the past been spared much of the damage seen in other parts of the country.

Strikes were also reported in the southern Zaporizhzhya region, home to Europe's largest nuclear power plant.

In Dnipro -- with a pre-war population of nearly 1 million -- a strike on a residential building killed at least five people and injured dozens, according to regional officials.

"There are five dead already," regional Governor Valentyn Reznichenko said on Telegram, adding that nearly 60 people were hurt, including 12 children.

Zelenskiy, in a Telegram posting, said, "Eternal memory to all whose lives were taken by Russian terror! The world must stop this evil."

“We will find everyone involved in this terror. Everyone will bear responsibility. Utmost responsibility,” he added. (KB/RFE-RL)