Kyiv has been struck by multiple explosions, prompting Ukraine to raise its alert level as Russia initiated a series of airstrikes. Lviv, which shares a border with Poland, was also targeted, with one cruise missile breaching Polish airspace, according to the country's armed forces.

The attacks commenced in the capital at 05:00 local time (03:00 GMT). Ukrainian military forces reported actively engaging their air defense systems to fend off the assault.

Serhiy Popko, head of Kyiv's military administration, disclosed that approximately a dozen Russian missiles had been intercepted over the capital and its surroundings.

He reassured that there have been no reported casualties or significant damage resulting from the attacks, as stated in a Telegram announcement.

Andriy Sadovyi, the mayor of Lviv, conveyed via Telegram that while the city itself remained unscathed, the broader Lviv region experienced approximately 20 missile strikes and seven drone attacks targeting critical infrastructure.

"The object entered Polish space near the town of Oserdow and stayed there for 39 seconds. During the entire flight, it was observed by military radar systems," the armed forces said in a statement.

Residents in the Ukrainian capital have been pictured taking shelter in metro stations.

It comes after Russia fired dozens of missiles on Friday, hitting a dam and leaving a million Ukrainians without power.

Moscow has not yet commented on Sunday's strikes.

The Russian-installed governor of the port of Sevastopol, in annexed Crimea, said Russian forces had shot down 10 Ukrainian missiles over the city late on Saturday.

An office building and a gas line were destroyed and a woman suffered a shrapnel injury, Mikhail Razvozhayev said on Telegram.